Kikkoman Corporation

Yasuko Tanabe

Kozo Hirokawa

Atsushi Ichiyanagi

Yosuke Masakari

Ryoko Tajima

Eriko Yoshihara

This invention provides an amadoriase having high substrate specificity to fructosyl valyl histidine. Such amadoriase comprises substitution of one or more amino acid residues at positions corresponding to amino acids selected from the group consisting of position 98, position 259, position 154, position 125, position 261, position 263, position 106, position 103, position 355, position 96, position 66, position 67, position 70, position 100, position 110, position 113, position 114, and position 156 in the amadoriase derived from the genus. This invention enables accurate measurement of &#x3b1;-fructosyl valyl histidine derived from the &#x3b2;-chain amino terminus in glycated hemoglobin in the presence of &#x3b5;-fructosyl lysine.

Amadoriase having altered substrate specificity

A flavin-binding glucose dehydrogenase (FAD-GDH), which in addition to having high substrate specificity and adequate desirable heat stability, is suitable for efficient production, preferably using, yeast or molds and the like as host cells. The FAD-GDH has amino acid substitutions at positions equivalent to one or more locations selected from the group consisting of position 213, position 368 and position 526 in the amino acid sequence described in SEQ ID NO: 8. The FAD-GDH is acquired from a culture by inserting a gene encoding the FAD-GDH into host cells such as. A preferable example of the FAD-GDH is FAD-GDH, in which a signal peptide region present in an N-terminal region has been deleted from the amino acid sequence of Mucor-derived FAD-GDH, and which has the aforementioned amino acid substitutions. The FAD-GDH can be preferably used in clinical diagnosis.

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Chiba, Japan

Yasuko Tanabe