Kikkoman Corporation

Airi Komatsuzaki

Atsushi Ichiyanagi

Yosuke Masakari

Provided are an amadoriase that is less likely to be influenced by oxygen concentration and a method and a reagent kit for measurement of HbA1c using such amadoriase. Provided are an amadoriase that is obtained via substitution of one or more amino acid residues at a position or positions corresponding to the position(s) selected from the group consisting of positions 280, 267, 269, 54, and 241 of the amadoriase derived from the genus, a method for measurement of HbA1c, a reagent kit for measurement, and a sensor using such amadoriase. The modified amadoriase according to the invention has a lowered oxidase activity and an enhanced dehydrogenase activity, and this enables the use of an electron mediator, and this reduces the influence of oxygen concentration. Thus, HbA1c can be measured with high sensitivity.

Amadoriase having enhanced dehydrogenase activity

The present invention provides a composition that enables measurement of glycated hemoglobin in the presence of a stronger surfactant than conventional surfactants. To this end, the present invention provides an amadoriase in which one or more amino acids have been substituted at positions corresponding to positions selected from the group consisting of positions 80, 71, 175, 172, 279, 12, 9, 77, 30, 28, 13, 3, 4, 286, 204, 338, 44, 340, and 194 of the amadoriase derived from the genushaving the amino acid sequence as shown in SEQ ID NO: 1 as well as a composition for measurement of glycated hemoglobin comprising an amadoriase that retains activity in the presence of an anionic surfactant. The present invention can provide an enzyme and a composition for measurement of glycated hemoglobin that sufficiently remain stable even when exposed to anionic surfactants.

Amadoriase having enhanced anionic surfactant tolerance

This invention provides an amadoriase having improved specific activity on a glycated substrate, compared with conventional amadoriase. Provided is an amadoriase comprising a substitution of the amino acid at the position corresponding to position 64 of the amino acid sequence as shown in SEQ ID NO: 1 with an amino acid selected from the group consisting of glycine, serine, methionine, leucine, threonine, valine, and isoleucine, a method for measurement of HbA1c, and a reagent kit for measurement of HbA1c using such amadoriase. Such method and kit for measurement enable rapid, simple, and accurate quantification of HbA1c.

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Noda, Japan

Airi Komatsuzaki