Fructosyl-peptide Oxidase (FPOX-CE)

  • Enzymes for Clinical Chemistry

The enzyme is useful for the determination of fructosyl-peptide and fructosyl-L-amino acid.

Origin recombinant E. coli
Systematic name

Fructosyl-peptide : oxygen oxidoreductase

EC Number 1.5.3
Reaction formula

Fructosyl-L-amino acid + H2O + O2 →→→ Peptide + Glucosone + H2O2


Appearance yellow lyophilizate

≧6.0 U/mg

Contaminants Catalase ≦1.0 U/U%
Stabilizer ethylenediaminetetraacetic acid (EDTA), sodium glutamate
Storage condition below -20℃ protected from light


Molecular weight ca. 60kDa (gel filtration)
Structure monomer of 52 kDa (SDS-PAGE)
Isoelectric point 4.2
Michaelis constant 3.4×10-3M (fructosyl-valyl-histidine)
4.4×10-3M (fructosyl-glycine)
8.9×10-3M (Nε-fructosyl-lysine)
pH Optimum 7.5–8.0
pH Stability 6.0–9.5
Optimum temperature 35–42℃
Thermal stability below 45℃
Stability (powder form) stable at 37℃ for at least one month
Specificity fructosyl-valyl-histidine (100), fructosyl-glycine (53)
Nε-fructosyl-lysine (84)


The enzyme is useful for the determination of fructosyl-peptide and fructosyl-L-amino acid.

Development history

Fructosyl-peptide Oxidase

One of the indexes used in the diagnosis of diabetes is glycated hemoglobin (HbA1c). The measurement of HbA1c using enzymes is suitable for processing large numbers of specimens, and is cost efficient. As such, there has long been a strong call from health practitioners for the development of such an enzyme assay. Therefore, we developed a new assay using the “dipeptide method”. Specifically, we discovered “Fructosyl-peptide Oxidase” (FPOX) which could be used as an enzyme for this assay. This facilitated our success in achieving a world’s first by making a reality of an HbA1c enzyme assay. This “dipeptide method” uses Protease (Proteolytic enzyme) to break down HbA1c in the bloodstream, and then measures the levels of saccharified dipeptides produced using FPOX. This method met with an overwhelmingly positive reception due to its merits of being simple, inexpensive and speedy, and the HbA1c measuring reagent using FPOX has now come to be used throughout the world.



Hirokawa K, Gomi K, Bakke M, Kajiyama N. (2003)
Distribution and properties of novel deglycating enzymes for fructosyl peptide in fungi.
Archives of Microbiology, 180, 227-231.

Hirokawa K, Gomi K, Kajiyama N. (2003)
Molecular cloning and expression of novel fructosyl peptide oxidases and their application for the measurement of glycated protein.
Biochem Biophys Res Commun, 311(1), 104-111.

Hirokawa K, Shimoji K, Kajiyama N. (2005)
An enzymatic method for the determination of hemoglobinA1C.
Biotechnology Letters, 27(14), 963-968.