Modified ß-galactosidase

A modified β-galactosidase consisting of an amino acid sequence in which one or more amino acids selected from the group consisting of tryptophan at position 85 (W85), phenylalanine at position 91 (F91), tyrosine at position 103 (Y103), tyrosine at position 134 (Y134), tyrosine at position 153 (Y153), proline at position 182 (P182), tryptophan at position 186 (W186), tyrosine at position 192 (Y192), tyrosine at position 295 (Y295), histidine at position 345 (H345), glycine at position 349 (G349), phenylalanine at position 402 (F402), glutamine at position 407 (Q407), glycine at position 479 (G479), glutamic acid at position 480 (E480), lysine at position 482 (K482), threonine at position 483 (T483), arginine at position 484 (R484), glycine at position 485 (G485), aspartic acid at position 486 (D486), lysine at position 487 (K487), valine at position 488 (V488), tyrosine at position 496 (Y496), serine at position 512 (S512), glutamic acid at position 513 (E513), asparagine at position 514 (N514), asparagine at position 515 (N515), tyrosine at position 516 (Y516), aspartic acid at position 517 (D517), tyrosine at position 519 (Y519), threonine at position 533 (T533), tyrosine at position 547 (Y547), tyrosine at position 549 (Y549), tyrosine at position 555 (Y555), arginine at position 572 (R572), threonine at position 573 (T573), tyrosine at position 598 (Y598), tyrosine at position 605 (Y605), tyrosine at position 606 (Y606), tyrosine at position 609 (Y609), phenylalanine at position 616 (F616), phenylalanine at position 624 (F624), tryptophan at position 648 (W648), and tryptophan at position 650 (W650), or an amino acid(s) corresponding thereto, has/have been substituted by other amino acid in a β-galactosidase consisting of the amino acid sequence of any of SEQ ID NOs. 1 to 4 or an amino acid sequence having 90% or more identity to the amino acid sequence set forth in any of SEQ ID NOs. 1 to 4.

A modified β-galactosidase, wherein the modified β-galactosidase has undergone any of the following modifications in a β-galactosidase consisting of the amino acid sequence of any of SEQ ID NOs. 1 to 4 or an amino acid sequence having 90% or more identity to the amino acid sequence set forth in any of SEQ ID NOs. 1 to 4:

• a double substitution in which the serine at position 188 or an amino acid corresponding thereto is substituted with isoleucine and the asparagine at position 550 or an amino acid corresponding thereto is substituted with phenylalanine (S188I_N550F);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with arginine and the asparagine at position 550 or an amino acid corresponding thereto is substituted with phenylalanine (Q407R_N550F);
• a double substitution in which the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamine and the tyrosine at position 598 or an amino acid corresponding thereto is substituted with histidine (Y449Q_Y598H);
• a double substitution in which the asparagine at position 550 or an amino acid corresponding thereto is substituted with phenylalanine and the proline at position 602 or an amino acid corresponding thereto is substituted with glutamine (N550F_P602Q);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with arginine and the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamic acid (Q407R_Y449E);
• a double substitution in which the asparagine at position 550 or an amino acid corresponding thereto is substituted with phenylalanine and the tyrosine at position 598 or an amino acid corresponding thereto is substituted with asparagine (N550F_Y598N);
• a double substitution in which the proline at position 182 or an amino acid corresponding thereto is substituted with leucine and the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamic acid (P182L_Y449E);
• a double substitution in which the proline at position 182 or an amino acid corresponding thereto is substituted with leucine and the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamine (P182L_Y449Q);
• a double substitution in which the tyrosine at position 187 or an amino acid corresponding thereto is substituted with leucine and the glutamine at position 407 or an amino acid corresponding thereto is substituted with arginine (Y187L_Q407R);
• a double substitution in which the tyrosine at position 187 or an amino acid corresponding thereto is substituted with leucine and the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamic acid (Y187L_Y449E);
• a double substitution in which the tyrosine at position 187 or an amino acid corresponding thereto is substituted with leucine and the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamine (Y187L_Y449Q);
• a double substitution in which the tyrosine at position 187 or an amino acid corresponding thereto is substituted with leucine and the serine at position 512 or an amino acid corresponding thereto is substituted with cysteine (Y187L_S512C);
• a double substitution in which the tyrosine at position 187 or an amino acid corresponding thereto is substituted with leucine and the serine at position 512 or an amino acid corresponding thereto is substituted with asparagine (Y187L_S512N);
• a double substitution in which the tyrosine at position 187 or an amino acid corresponding thereto is substituted with leucine and the serine at position 512 or an amino acid corresponding thereto is substituted with threonine (Y187L_S512T);
• a double substitution in which the serine at position 188 or an amino acid corresponding thereto is substituted with isoleucine and the glutamine at position 407 or an amino acid corresponding thereto is substituted with arginine (S188I_Q407R);
• a double substitution in which the serine at position 188 or an amino acid corresponding thereto is substituted with isoleucine and the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamine (S188I_Y449Q);
• a double substitution in which the serine at position 188 or an amino acid corresponding thereto is substituted with isoleucine and the threonine at position 483 or an amino acid corresponding thereto is substituted with glutamic acid (S188I_T483E);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with leucine and the serine at position 512 or an amino acid corresponding thereto is substituted with valine (Q407L_S512V);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with arginine and the threonine at position 483 or an amino acid corresponding thereto is substituted with glycine (Q407R_T483G);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with arginine and the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamine (Q407R_Y449Q);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with arginine and the asparagine at position 550 or an amino acid corresponding thereto is substituted with serine (Q407R_N550S);
• a double substitution in which the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamine and the asparagine at position 550 or an amino acid corresponding thereto is substituted with serine (Y449Q_N550S);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with tryptophan and the serine at position 512 or an amino acid corresponding thereto is substituted with threonine (K487W_S512T);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with tryptophan and the aspartic acid at position 517 or an amino acid corresponding thereto is substituted with lysine (K487W_D517K);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with tryptophan and the asparagine at position 515 or an amino acid corresponding thereto is substituted with glycine (K487W_N515G);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with tryptophan and the aspartic acid at position 517 or an amino acid corresponding thereto is substituted with tryptophan (K487W_D517W);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with proline and the asparagine at position 515 or an amino acid corresponding thereto is substituted with arginine (K487P_N515R);
• a double substitution in which the phenylalanine at position 91 or an amino acid corresponding thereto is substituted with serine and the glutamine at position 407 or an amino acid corresponding thereto is substituted with methionine (F91S_Q407M);
• a double substitution in which the threonine at position 180 or an amino acid corresponding thereto is substituted with valine and the tyrosine at position 187 or an amino acid corresponding thereto is substituted with leucine (T180V_Y187L);
• a double substitution in which the threonine at position 180 or an amino acid corresponding thereto is substituted with valine and the serine at position 188 or an amino acid corresponding thereto is substituted with isoleucine (T180V_S188I);
• a double substitution in which the threonine at position 180 or an amino acid corresponding thereto is substituted with valine and the glutamine at position 407 or an amino acid corresponding thereto is substituted with arginine (T180V_Q407R);
• a double substitution in which the threonine at position 180 or an amino acid corresponding thereto is substituted with valine and the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamic acid (T180V_Y449E);
• a double substitution in which the threonine at position 180 or an amino acid corresponding thereto is substituted with valine and the threonine at position 483 or an amino acid corresponding thereto is substituted with glycine (T180V_T483G);
• a double substitution in which the threonine at position 180 or an amino acid corresponding thereto is substituted with valine and the serine at position 512 or an amino acid corresponding thereto is substituted with valine (T180V_S512V);
• a double substitution in which the threonine at position 180 or an amino acid corresponding thereto is substituted with valine and the asparagine at position 550 or an amino acid corresponding thereto is substituted with phenylalanine (T180V_N550F);
• a double substitution in which the threonine at position 180 or an amino acid corresponding thereto is substituted with valine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with proline (T180V_Y615P);
• a double substitution in which the proline at position 182 or an amino acid corresponding thereto is substituted with leucine and the arginine at position 376 or an amino acid corresponding thereto is substituted with proline (P182L_R376P);
• a double substitution in which the proline at position 182 or an amino acid corresponding thereto is substituted with tryptophan and the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamine (P182W_Y449Q);
• a double substitution in which the tyrosine at position 187 or an amino acid corresponding thereto is substituted with leucine and the lysine at position 487 or an amino acid corresponding thereto is substituted with alanine (Y187L_K487A);
• a double substitution in which the tyrosine at position 187 or an amino acid corresponding thereto is substituted with leucine and the serine at position 512 or an amino acid corresponding thereto is substituted with alanine (Y187L_S512A);
• a double substitution in which the tyrosine at position 187 or an amino acid corresponding thereto is substituted with leucine and the threonine at position 533 or an amino acid corresponding thereto is substituted with asparagine (Y187L_T533N);
• a double substitution in which the arginine at position 376 or an amino acid corresponding thereto is substituted with proline and the glutamine at position 407 or an amino acid corresponding thereto is substituted with leucine (R376P_Q407L);
• a double substitution in which the arginine at position 376 or an amino acid corresponding thereto is substituted with proline and the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamine (R376P_Y449Q);
• a double substitution in which the arginine at position 376 or an amino acid corresponding thereto is substituted with proline and the serine at position 512 or an amino acid corresponding thereto is substituted with valine (R376P_S512V);
• a double substitution in which the arginine at position 376 or an amino acid corresponding thereto is substituted with proline and the asparagine at position 550 or an amino acid corresponding thereto is substituted with tryptophan (R376P_N550W);
• a double substitution in which the arginine at position 376 or an amino acid corresponding thereto is substituted with proline and the asparagine at position 550 or an amino acid corresponding thereto is substituted with tyrosine (R376P_N550Y);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with leucine and the threonine at position 533 or an amino acid corresponding thereto is substituted with glutamic acid (Q407L_T533E);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with leucine and the tryptophan at position 570 or an amino acid corresponding thereto is substituted with tyrosine (Q407L_W570Y);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with leucine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with leucine (Q407L_Y615L);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with arginine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with leucine (Q407R_Y615L);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with arginine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with proline (Q407R_Y615P);
• a double substitution in which the tyrosine at position 449 or an amino acid corresponding thereto is substituted with aspartic acid and the tyrosine at position 598 or an amino acid corresponding thereto is substituted with phenylalanine (Y449D_Y598F);
• a double substitution in which the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamine and the threonine at position 533 or an amino acid corresponding thereto is substituted with glutamic acid (Y449Q_T533E);
• a double substitution in which the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with glycine (Y449Q_Y615G);
• a double substitution in which the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with proline (Y449Q_Y615P);
• a double substitution in which the threonine at position 483 or an amino acid corresponding thereto is substituted with glycine and the serine at position 512 or an amino acid corresponding thereto is substituted with valine (T483G_S512V);
• a double substitution in which the threonine at position 483 or an amino acid corresponding thereto is substituted with glycine and the asparagine at position 550 or an amino acid corresponding thereto is substituted with serine (T483G_N550S);
• a double substitution in which the threonine at position 483 or an amino acid corresponding thereto is substituted with glycine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with leucine (T483G_Y615L);
• a double substitution in which the threonine at position 483 or an amino acid corresponding thereto is substituted with glutamine and the proline at position 602 or an amino acid corresponding thereto is substituted with glutamine (T483Q_P602Q);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with histidine and the lysine at position 487 or an amino acid corresponding thereto is substituted with histidine (R484H_K487H);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with tryptophan and the lysine at position 487 or an amino acid corresponding thereto is substituted with aspartic acid (R484W_K487D);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with tryptophan and the threonine at position 575 or an amino acid corresponding thereto is substituted with tryptophan (R484W_T575W);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the valine at position 488 or an amino acid corresponding thereto is substituted with tryptophan (G485K_V488W);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the tyrosine at position 516 or an amino acid corresponding thereto is substituted with tryptophan (G485K_Y516W);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the aspartic acid at position 517 or an amino acid corresponding thereto is substituted with lysine (G485K_D517K);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the aspartic acid at position 517 or an amino acid corresponding thereto is substituted with tryptophan (G485K_D517W);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the glycine at position 569 or an amino acid corresponding thereto is substituted with tryptophan (G485K_G569W);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the glycine at position 571 or an amino acid corresponding thereto is substituted with lysine (G485K_G571K);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the arginine at position 572 or an amino acid corresponding thereto is substituted with tryptophan (G485K_R572W);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the threonine at position 573 or an amino acid corresponding thereto is substituted with tryptophan (G485K_T573W);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with tryptophan and the tyrosine at position 516 or an amino acid corresponding thereto is substituted with tryptophan (G485W_Y516W);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with tryptophan and the aspartic acid at position 517 or an amino acid corresponding thereto is substituted with tryptophan (G485W_D517W);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with tryptophan and the threonine at position 573 or an amino acid corresponding thereto is substituted with lysine (G485W_T573K);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with tryptophan and the threonine at position 573 or an amino acid corresponding thereto is substituted with tryptophan (G485W_T573W);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with alanine and the serine at position 512 or an amino acid corresponding thereto is substituted with valine (K487A_S512V);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with glycine and the asparagine at position 515 or an amino acid corresponding thereto is substituted with glutamine (K487G_N515Q);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with tryptophan and the threonine at position 573 or an amino acid corresponding thereto is substituted with lysine (K487W_T573K);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with tryptophan and the tryptophan at position 593 or an amino acid corresponding thereto is substituted with phenylalanine (K487W_W593F);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with lysine and the asparagine at position 514 or an amino acid corresponding thereto is substituted with lysine (V488K_N514K);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with lysine and the aspartic acid at position 517 or an amino acid corresponding thereto is substituted with lysine (V488K_D517K);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with lysine and the glycine at position 569 or an amino acid corresponding thereto is substituted with lysine (V488K_G569K);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with lysine and the glycine at position 569 or an amino acid corresponding thereto is substituted with tryptophan (V488K_G569W);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with lysine and the arginine at position 572 or an amino acid corresponding thereto is substituted with lysine (V488K_R572K);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with lysine and the threonine at position 573 or an amino acid corresponding thereto is substituted with lysine (V488K_T573K);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with lysine and the threonine at position 573 or an amino acid corresponding thereto is substituted with tryptophan (V488K_T573W);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with lysine and the tyrosine at position 516 or an amino acid corresponding thereto is substituted with lysine (V488K_Y516K);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with lysine and the tyrosine at position 516 or an amino acid corresponding thereto is substituted with tryptophan (V488K_Y516W);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with tryptophan and the asparagine at position 514 or an amino acid corresponding thereto is substituted with tryptophan (V488W_N514W);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with tryptophan and the threonine at position 573 or an amino acid corresponding thereto is substituted with tryptophan (V488W_T573W);
• a double substitution in which the glutamic acid at position 500 or an amino acid corresponding thereto is substituted with alanine and the isoleucine at position 501 or an amino acid corresponding thereto is substituted with alanine (E500A_I501A);
• a double substitution in which the serine at position 512 or an amino acid corresponding thereto is substituted with valine and the asparagine at position 550 or an amino acid corresponding thereto is substituted with serine (S512V_N550S);
• a double substitution in which the threonine at position 533 or an amino acid corresponding thereto is substituted with glutamic acid and the asparagine at position 550 or an amino acid corresponding thereto is substituted with serine (T533E_N550S);
• a double substitution in which the threonine at position 533 or an amino acid corresponding thereto is substituted with glutamic acid and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with glycine (T533E_Y615G);
• a double substitution in which the tryptophan at position 570 or an amino acid corresponding thereto is substituted with tyrosine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with leucine (W570Y_Y615L);
• a double substitution in which the phenylalanine at position 91 or an amino acid corresponding thereto is substituted with valine and the glutamic acid at position 513 or an amino acid corresponding thereto is substituted with glycine (F91V_E513G);
• a double substitution in which the threonine at position 180 or an amino acid corresponding thereto is substituted with valine and the threonine at position 483 or an amino acid corresponding thereto is substituted with lysine (T180V_T483K);
• a double substitution in which the threonine at position 180 or an amino acid corresponding thereto is substituted with valine and the tyrosine at position 598 or an amino acid corresponding thereto is substituted with asparagine (T180V_Y598N);
• a double substitution in which the threonine at position 180 or an amino acid corresponding thereto is substituted with valine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with glycine (T180V_Y615G);
• a double substitution in which the proline at position 182 or an amino acid corresponding thereto is substituted with leucine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with leucine (P182L_Y615L);
• a double substitution in which the arginine at position 376 or an amino acid corresponding thereto is substituted with proline and the tyrosine at position 598 or an amino acid corresponding thereto is substituted with asparagine (R376P_Y598N);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with leucine and the threonine at position 483 or an amino acid corresponding thereto is substituted with lysine (Q407L_T483K);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with leucine and the lysine at position 487 or an amino acid corresponding thereto is substituted with proline (Q407L_K487P);
• a double substitution in which the glutamine at position 407 or an amino acid corresponding thereto is substituted with leucine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with glycine (Q407L_Y615G);
• a double substitution in which the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamic acid and the lysine at position 487 or an amino acid corresponding thereto is substituted with alanine (Y449E_K487A);
• a double substitution in which the tyrosine at position 449 or an amino acid corresponding thereto is substituted with glutamic acid and the lysine at position 487 or an amino acid corresponding thereto is substituted with proline (Y449E_K487P);
• a double substitution in which the threonine at position 483 or an amino acid corresponding thereto is substituted with glycine and the lysine at position 487 or an amino acid corresponding thereto is substituted with alanine (T483G_K487A);
• a double substitution in which the threonine at position 483 or an amino acid corresponding thereto is substituted with glycine and the threonine at position 533 or an amino acid corresponding thereto is substituted with glutamic acid (T483G_T533E);
• a double substitution in which the threonine at position 483 or an amino acid corresponding thereto is substituted with glycine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with glycine (T483G_Y615G);
• a double substitution in which the threonine at position 483 or an amino acid corresponding thereto is substituted with methionine and the lysine at position 487 or an amino acid corresponding thereto is substituted with alanine (T483M_K487A);
• a double substitution in which the threonine at position 483 or an amino acid corresponding thereto is substituted with methionine and the lysine at position 487 or an amino acid corresponding thereto is substituted with glycine (T483M_K487G);
• a double substitution in which the threonine at position 483 or an amino acid corresponding thereto is substituted with methionine and the lysine at position 487 or an amino acid corresponding thereto is substituted with proline (T483M_K487P);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with histidine and the lysine at position 487 or an amino acid corresponding thereto is substituted with aspartic acid (R484H_K487D);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the glutamic acid at position 513 or an amino acid corresponding thereto is substituted with tryptophan (R484K_E513W);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the asparagine at position 514 or an amino acid corresponding thereto is substituted with lysine (R484K_N514K);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the asparagine at position 514 or an amino acid corresponding thereto is substituted with tryptophan (R484K_N514W);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the asparagine at position 515 or an amino acid corresponding thereto is substituted with lysine (R484K_N515K);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the asparagine at position 515 or an amino acid corresponding thereto is substituted with tryptophan (R484K_N515W);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the aspartic acid at position 517 or an amino acid corresponding thereto is substituted with tryptophan (R484K_D517W);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the glycine at position 569 or an amino acid corresponding thereto is substituted with lysine (R484K_G569K);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the glycine at position 571 or an amino acid corresponding thereto is substituted with lysine (R484K_G571K);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the arginine at position 572 or an amino acid corresponding thereto is substituted with lysine (R484K_R572K);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the arginine at position 572 or an amino acid corresponding thereto is substituted with tryptophan (R484K_R572W);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the threonine at position 573 or an amino acid corresponding thereto is substituted with lysine (R484K_T573K);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the threonine at position 573 or an amino acid corresponding thereto is substituted with tryptophan (R484K_T573W);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with lysine and the tyrosine at position 516 or an amino acid corresponding thereto is substituted with lysine (R484K_Y516K);
• a double substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with tryptophan and the asparagine at position 515 or an amino acid corresponding thereto is substituted with lysine (R484W_N515K);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with aspartic acid and the lysine at position 487 or an amino acid corresponding thereto is substituted with histidine (G485D_K487H);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the lysine at position 487 or an amino acid corresponding thereto is substituted with histidine (G485K_K487H);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the glycine at position 569 or an amino acid corresponding thereto is substituted with lysine (G485K_G569K);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the asparagine at position 514 or an amino acid corresponding thereto is substituted with lysine (G485K_N514K);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the asparagine at position 515 or an amino acid corresponding thereto is substituted with lysine (G485K_N515K);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with lysine and the asparagine at position 515 or an amino acid corresponding thereto is substituted with tryptophan (G485K_N515W);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with arginine and the lysine at position 487 or an amino acid corresponding thereto is substituted with aspartic acid (G485R_K487D);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with tryptophan and the glutamic acid at position 513 or an amino acid corresponding thereto is substituted with tryptophan (G485W_E513W);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with tryptophan and the asparagine at position 515 or an amino acid corresponding thereto is substituted with lysine (G485W_N515K);
• a double substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with tryptophan and the asparagine at position 515 or an amino acid corresponding thereto is substituted with tryptophan (G485W_N515W);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with alanine and the serine at position 531 or an amino acid corresponding thereto is substituted with alanine (K487A_S531A);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with alanine and the tryptophan at position 593 or an amino acid corresponding thereto is substituted with phenylalanine (K487A_W593F);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with alanine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with leucine (K487A_Y615L);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with tryptophan and the asparagine at position 514 or an amino acid corresponding thereto is substituted with lysine (K487W_N514K);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with tryptophan and the asparagine at position 514 or an amino acid corresponding thereto is substituted with tryptophan (K487W_N514W);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with tryptophan and the tyrosine at position 516 or an amino acid corresponding thereto is substituted with tryptophan (K487W_Y516W);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with tryptophan and the glycine at position 569 or an amino acid corresponding thereto is substituted with lysine (K487W_G569K);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with tyrosine and the asparagine at position 515 or an amino acid corresponding thereto is substituted with phenylalanine (K487Y_N515F);
• a double substitution in which the lysine at position 487 or an amino acid corresponding thereto is substituted with tyrosine and the asparagine at position 515 or an amino acid corresponding thereto is substituted with tryptophan (K487Y_N515W);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with lysine and the asparagine at position 515 or an amino acid corresponding thereto is substituted with lysine (V488K_N515K);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with lysine and the asparagine at position 515 or an amino acid corresponding thereto is substituted with tryptophan (V488K_N515W);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with tryptophan and the asparagine at position 515 or an amino acid corresponding thereto is substituted with lysine (V488W_N515K);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with tryptophan and the asparagine at position 515 or an amino acid corresponding thereto is substituted with tryptophan (V488W_N515W);
• a double substitution in which the valine at position 488 or an amino acid corresponding thereto is substituted with tyrosine and the asparagine at position 515 or an amino acid corresponding thereto is substituted with tryptophan (V488Y_N515W);
• a double substitution in which the asparagine at position 550 or an amino acid corresponding thereto is substituted with serine and the tyrosine at position 598 or an amino acid corresponding thereto is substituted with asparagine (N550S_Y598N);
• a double substitution in which the asparagine at position 550 or an amino acid corresponding thereto is substituted with serine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with glycine (N550S_Y615G);
• a double substitution in which the asparagine at position 550 or an amino acid corresponding thereto is substituted with serine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with leucine (N550S_Y615L);
• a double substitution in which the asparagine at position 550 or an amino acid corresponding thereto is substituted with serine and the tyrosine at position 615 or an amino acid corresponding thereto is substituted with proline (N550S_Y615P);
• a triple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with alanine, the glycine at position 485 or an amino acid corresponding thereto is substituted with alanine, and the lysine at position 487 or an amino acid corresponding thereto is substituted with aspartic acid (R484A_G485A_K487D);
• a triple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with aspartic acid, the glycine at position 485 or an amino acid corresponding thereto is substituted with aspartic acid, and the lysine at position 487 or an amino acid corresponding thereto is substituted with aspartic acid (R484D_G485D_K487D);
• a triple substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with arginine, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with arginine, and the lysine at position 487 or an amino acid corresponding thereto is substituted with arginine (G485R_D486R_K487R);
• a quadruple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with alanine, the glycine at position 485 or an amino acid corresponding thereto is substituted with alanine, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with alanine, and the lysine at position 487 or an amino acid corresponding thereto is substituted with alanine (R484A_G485A_D486A_K487A);
• a quadruple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with alanine, the glycine at position 485 or an amino acid corresponding thereto is substituted with alanine, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with proline, and the lysine at position 487 or an amino acid corresponding thereto is substituted with proline (R484A_G485A_D486P_K487P);
• a triple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with alanine, the glycine at position 485 or an amino acid corresponding thereto is substituted with alanine, and the lysine at position 487 or an amino acid corresponding thereto is substituted with aspartic acid (R484A_G485A_K487D);
• a triple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with cysteine, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with histidine, and the lysine at position 487 or an amino acid corresponding thereto is substituted with arginine (R484C_D486H_K487R);
• a triple substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with arginine, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with tryptophan, and the lysine at position 487 or an amino acid corresponding thereto is substituted with tryptophan (G485R_D486W_K487W);
• a triple substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with arginine, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with alanine, and the lysine at position 487 or an amino acid corresponding thereto is substituted with alanine (G485R_D486A_K487A);
• a triple substitution in which the glycine at position 485 or an amino acid corresponding thereto is substituted with arginine, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with proline, and the lysine at position 487 or an amino acid corresponding thereto is substituted with proline (G485R_D486P_K487P);
• a quadruple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with alanine, the glycine at position 485 or an amino acid corresponding thereto is substituted with alanine, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with alanine, and the lysine at position 487 or an amino acid corresponding thereto is substituted with alanine (R484A_G485A_D486A_K487A);
• a quadruple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with alanine, the glycine at position 485 or an amino acid corresponding thereto is substituted with alanine, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with arginine, and the lysine at position 487 or an amino acid corresponding thereto is substituted with arginine (R484A_G485A_D486R_K487R);
• a quadruple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with aspartic acid, the glycine at position 485 or an amino acid corresponding thereto is substituted with aspartic acid, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with arginine, and the lysine at position 487 or an amino acid corresponding thereto is substituted with arginine (R484D_G485D_D486R_K487R);
• a quadruple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with aspartic acid, the glycine at position 485 or an amino acid corresponding thereto is substituted with aspartic acid, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with proline, and the lysine at position 487 or an amino acid corresponding thereto is substituted with proline (R484D_G485D_D486P_K487P);
• a quadruple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with aspartic acid, the glycine at position 485 or an amino acid corresponding thereto is substituted with aspartic acid, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with alanine, and the lysine at position 487 or an amino acid corresponding thereto is substituted with alanine (R484D_G485D_D486A_K487A);
• a quadruple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with aspartic acid, the glycine at position 485 or an amino acid corresponding thereto is substituted with aspartic acid, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with tryptophan, and the lysine at position 487 or an amino acid corresponding thereto is substituted with tryptophan (R484D_G485D_D486W_K487W);
• and
• a quadruple substitution in which the arginine at position 484 or an amino acid corresponding thereto is substituted with proline, the glycine at position 485 or an amino acid corresponding thereto is substituted with proline, the aspartic acid at position 486 or an amino acid corresponding thereto is substituted with arginine, and the lysine at position 487 or an amino acid corresponding thereto is substituted with arginine (R484P_G485P_D486R_K487R).

A modified β-galactosidase, wherein the modified β-galactosidase has undergone any of the following modifications in a β-galactosidase consisting of the amino acid sequence of any of SEQ ID NOs. 1 to 4 or an amino acid sequence having 90% or more identity to the amino acid sequence set forth in any of SEQ ID NOs. 1 to 4:

• (a) a deletion of the region of arginine at position 484 (R484) to lysine at position 487 (K487) or a region corresponding thereto;
• (b) an insertion of an amino acid(s) at the position between asparagine at position 514 (N514) and asparagine at position 515 (N515) or at a position corresponding thereto;
• (c) an insertion of an amino acid(s) at the position between proline at position 604 (P604) and tyrosine at position 605 (Y605) or at a position corresponding thereto;
• (d) a deletion of the glycine at position 485 (G485) or an amino acid corresponding thereto, and in addition, a substitution of aspartic acid at position 486 (D486) or an amino acid corresponding thereto;
• (e) a deletion of the region of glycine at position 485 (G485) to aspartic acid at position 486 (D486) or a region corresponding thereto, and in addition, a substitution of lysine at position 487 (K487) or an amino acid corresponding thereto;
• (f) a deletion of the region of glycine at position 485 (G485) to aspartic acid at position 486 (D486) or a region corresponding thereto, and in addition, a substitution of arginine at position 484 (R484) or an amino acid corresponding thereto, and a substitution of lysine at position 487 (K487) or an amino acid corresponding thereto;
• (g) an insertion of an amino acid(s) at the position between arginine at position 484 (R484) and glycine at position 485 (G485) or at a position corresponding thereto;
• and
• (h) an insertion of an amino acid(s) at the position between glycine at position 485 (G485) and aspartic acid at position 486 (D486) or at a position corresponding thereto.

A modified β-galactosidase, wherein the modified β-galactosidase has undergone any of the following modifications in a β-galactosidase consisting of the amino acid sequence of SEQ ID NO. 1:

• (i) a substitution of the lysine at position 487 (K487) with glycine or proline;
• (ii) a substitution of the asparagine at position 514 (N514) with tryptophan;
• and
• (iii) a substitution of the asparagine at position 515 (N515) with lysine or tryptophan.