Disclosed is a modified glucose dehydrogenase having pyrroloquinoline
quinone as a coenzyme, wherein one or more amino acid residues in a
region of amino acid 349-377 of water-soluble PQQGDH derived from
Acinetobacter calcoaceticus is replaced with other amino acid residues
and has an inhibition constant (Ksi) of 200 mM or more. The modified
water-soluble PQQGDH of the invention can be utilized for measuring
glucose levels in the presence of high concentrations of glucose because
of the low substrate inhibition by glucose.