Patent ID: 7803592

Claim:
An isolated mutant glucose dehydrogenase exhibiting improved substrate specificity to glucose, which is (1) a mutant of the protein comprising the amino acid sequence of SEQ ID NO: 13, wherein said mutant consists of amino acid substitution(s) at positions 472 and/or 475 as listed below in (A)-(C); or (2) a mutant of the protein comprising the amino acid sequence of SEQ ID NO: 13 wherein said mutant consists of amino acid substitution(s) at positions 472 and/or 475 as listed below in (A)-(C) and consists of substitution, deletion, insertion or addition of one to ten amino acid residues at position(s) other than the positions listed below and wherein mutants (1) or (2) have glucose dehydrogenase activity (numerals represent a position in the amino acid sequence, the amino acid residues represent an amino acid residue after substitution at the position, and “+” means that two amino acid substitutions are simultaneously included), wherein improved substrate specificity for mutants (1) or (2) is a decrease of at least 10% in the ratio of reactivity to maltose/reactivity to glucose compared to the glucose dehydrogenase of SEQ ID NO: 13: (A) 472Arg, 472Asn, 472Asp, 472Cys, 472Glu, 472Gly, 472His, 472lle, 472Leu, 472Met, 472Phe, 472Pro, 472Ser, 472Trp, 472Tyr, or 472Val; (B) 475Asp, 475Cys, 475Glu, 475Gly, 475His, 475Met, 475Phe, 475Ser, 475Tyr, or 475Val; or (C) 472Arg +475(Asp, Glu, Gly, His, Phe, Ser, Tyr), 472Asn +475(Asp, Gly, His, Phe, Ser, Tyr), 472Asp +475(His, Phe, Ser, Val), 472Cys +475(Asp, Gly, His, Phe, Ser), 472Glu +475(Asp, Glu, Gly, His, Phe, Ser, Tyr), 472Gly +475(Asp, Cys, Gly, Met, Phe, Ser, Tyr), 472His +475(Cys, Glu, His, Met, Phe, Ser, Tyr), 472lle +475(Asp, Cys, Glu, Gly, His, Met, Phe, Ser, Tyr), 472Leu +475(Asp, Gly, His, Phe, Ser, Tyr), 472Met +475(Asp, Gly, His, Phe, Ser), 472Phe +475(Asp, Glu, Gly, His, Met, Phe, Ser, Tyr), 472Pro +475His 472Ser +475(Asp, Glu, Gly, His, Phe, Ser), 472Trp +475(His, Phe, Ser), 472Tyr +475(Asp, His, Phe, Ser), or 472Val +475(Asp, Glu, Gly, His, Phe, Ser).