Patent ID: 7588910

Claim:
A method of specifically determining a glycated β-chain N-terminal of glycated hemoglobin, the method comprising: reacting the glycated hemoglobin with enzymes comprising (i) a protease comprising carboxypeptidase B, neutral protease, carboxypeptidase A, thermolysin, Bacillus sp. ASP842 protease, Lysobacter enzymogenes YK-366 protease, or Aeromonas hydrophila NBRC 3820 protease, and (ii) a ketoamine oxidase having at least 75% sequence homology with SEQ ID NO: 1, without an operation for increasing the purity or concentration of glycated hemoglobin or a substance derived from glycated hemoglobin; wherein the ketoamine oxidase (ii) has a reactivity to ε-1-deoxyfructosyl-(α-benzyloxycarbonyl-L-lysine) of 30% or less compared with that to 1-deoxyfructosyl-L-valyl-L-histidine.