Patent ID: 8721853

Claim:
A device for assaying fructosyl valine, fructosyl valyl histidine, a fructosyl hexapeptide or HbA1c in a sample, comprising an electron transfer mediator and one of: a fructosyl peptidyl oxidase comprising an amino acid sequence having at least 90% identity with the amino acid sequence set forth in SEQ ID NO:1 and a Km value toward fructosyl valyl histidine of 1 mM or less; a fructosyl peptidyl oxidase comprising an amino acid sequence having at least 90% identity with the amino acid sequence set forth in SEQ ID NO:1 and a Vmax/Km value toward fructosyl valyl histidine of 10 U/mg·mM or more; and a fructosyl peptidyl oxidase comprising an amino acid sequence having at least 90% identity with the amino acid sequence set forth in SEQ ID NO:1 and residual activity of 50% or more when heat-treated at 50° C. for 10 minutes.