In one form, a fructosyl peptidyl oxidase derived from a budding yeast Phaeosphaeria nodorum for assaying a glycated protein in a sample is provided. The fructosyl peptidyl oxidase has higher activity toward fructosyl valine as well as fructosyl valyl histidine, and may be useful in assaying HbA1c with higher sensitivity and specificity. Still, other forms include unique methods, techniques, systems and devices involving a fructosyl peptidyl oxidase.