Patent ID: 7632667

Claim:
An isolated substrate-specific endonuclease V, which lacks a nonspecific nucleic acid cleavage activity; which exhibits a deoxyinosine-specific nucleic acid cleavage activity, and which is a mutant of a parent wild-type Thermotoga maritima endonuclease V of SEQ ID NO: 11, said mutant comprising an amino acid sequence which is identical to SEQ ID NO: 11 except for two amino acid replacements at the 80 th and the 105 th positions of the Thermotoga maritima endonuclease V of SEQ ID NO: 11 with amino acids X 1 and X 2 , respectively, wherein amino acids X 1 and X 2 differ from the amino acids replaced, wherein the amino acid X 1 is selected from the group consisting of alanine, glycine, leucine, isoleucine, valine, phenylalanine, and methionine, and the amino acid X 2 is selected from the group consisting of alanine, glycine, asparagine, glutamine, serine, threonine, and histidine, wherein the parent wild-type Thermotoga maritima endonuclease V of SEQ ID NO: 11 exhibits a nonspecific nucleic acid cleavage activity and exhibits a deoxyinosine specific nucleic acid cleavage activity; and wherein said two amino acid residue replacements result in the loss of the nonspecific nucleic acid cleavage activity found in the parent Thermotoga maritima endonuclease V of SEQ ID NO: 11 under the same conditions.