Patent ID: 7244600

Claim:
An isolated mutant water-soluble pyrrolo-quinoline quinine glucose dehydrogenase (PQQGDH) protein, wherein two subunits of said mutant PQQGDH are linked together via one or more disulfide bonds, wherein said mutant PQQGDH is a mutant of a PQQGDH comprising the amino acid sequence of SEQ ID NO:1 and wherein said mutant PQQGDH only has one or more amino acid substitutions selected from the group consisting of: (1) serine at position 415 is substituted with a cysteine residue in SEQ ID NO:1, (2) tyrosine at position 414 is substituted with a cysteine residue in SEQ ID NO:1, (3) aspartate at position 340 is substituted with a cysteine residue in SEQ ID NO:1, and (4) tyrosine at position 418 is substituted with a cysteine residue in SEQ ID NO:1.