Biotinylation of proteins

A method for immobilization of a protein, said method comprising:

• (a) on a surface of a substrate, providing avidin or streptavidin;
• (b) constructing a recombinant DNA expression vector that encodes a fusion protein, said fusion protein comprising said protein and a biotinylation peptide wherein said biotinylation peptide comprises an amino acid sequence defined by:
• LeuXaa1Xaa2IleXaa3Xaa4Xaa5Xaa6LysXaa7Xaa8Xaa9Xaa10 (SEQ ID NO:1), where Xaa1 is any amino acid;
• Xaa2 is any amino acid other than Leu, Val, Ile, Trp, Phe, or Tyr;
• Xaa3 is Phe or Leu;
• Xaa4 is Glu or Asp;
• Xaa5 is Ala, Gly, Ser, or Thr;
• Xaa6 is Gln or Met;
• Xaa7 is Ile, Met, or Val;
• Xaa8 is Glu, Leu, Val, Tyr, or Ile;
• Xaa9 is Trp, Tyr, Val, Phe, Leu, or Ile;
• and Xaa10 is any amino acid other than Asp or Glu, and wherein said biotinylation peptide is capable of being biotinylated by a biotin ligase at said lysine residue adjacent to Xaa6;
• and is 13 to 50 amino acids in length;
• (c) transforming a recombinant host cell with said vector;
• (d) culturing said host cell in the presence of biotin or a biotin analogue and under conditions such that said fusion protein and a biotinylation enzyme are expressed, resulting in biotinylation of said fusion protein;
• and
• (e) contacting said biotinylated fusion protein with a predefined region of the surface, whereby said biotinylated fusion protein is immobilized on such substrate.