Method for using heat-resistant mismatch endonuclease

A method of cleaving a double-stranded nucleic acid, the method comprising:

• treating a double-stranded nucleic acid having a mismatched base pair with at least one polypeptide selected from the group consisting of the following (i) to (iii) to cleave both strands of the double-stranded nucleic acid at the position of the mismatched base pair,
• (i) a polypeptide having an amino acid sequence of SEQ ID NO:7 or 8;
• (ii) a polypeptide having an amino acid sequence which differs from the amino acid sequence of SEQ ID NO:7 or 8 by substitution, deletion, insertion and/or addition of 1 to 10 amino acid residues, and having a mismatch endonuclease activity;
• and
• (iii) a polypeptide having an amino acid sequence which shares at least 75% amino acid sequence identity with the amino acid sequence of SEQ ID NO:7 or 8, and having a mismatch endonuclease activity,
• wherein the double-stranded nucleic acid is generated during a nucleic acid amplification process, and the cleaving is performed during or after the nucleic acid amplification process, and
• wherein the nucleic acid amplification process is performed by a polymerase chain reaction (PCR) method, a multiple displacement amplification (MDA) method or an isothermal nucleic acid amplification method.