Formate oxidase, an enzyme of the glucose-methanol-choline oxidoreductase family, has a His-Arg pair and 8-formyl-FAD at the catalytic site.
Doubayashi, D., Ootake, T., Maeda, Y., Oki, M., Tokunaga, Y., Sakurai, A., Nagaosa, Y., Mikami, B., Uchida, H.(2011) Biosci Biotechnol Biochem 75: 1662-1667
- PubMed: 21897046 
- DOI: https://doi.org/10.1271/bbb.110153
- Primary Citation of Related Structures:  
3Q9T - PubMed Abstract: 
Formate oxidase of Aspergillus oryzae RIB40 contains an 8-replaced FAD with molecular mass of 799 as cofactor. The ¹H-NMR spectrum of the cofactor fraction obtained from the enzyme indicated that the 8-replaced FAD in the fraction was 8-formyl-FAD, present in open form and hemiacetal form. The oxidation-reduction potentials of the open and hemiacetal forms were estimated by cyclic voltammetry to be -47 and -177 mV vs. Normal Hydrogen Electrode respectively. The structure of the enzyme was constructed using diffraction data to 2.24 Å resolution collected from a crystal of the enzyme. His₅₁₁ and Arg₅₅₄ were situated close to the pyrimidine part of the isoalloxazine ring of 8-formyl-FAD in open form. The enzyme had 8-formyl-FAD, the oxidation potential of which was approximately 160 mV more positive than that of FAD, and the His-Arg pair at the catalytic site, unlike the other enzymes belonging to the glucose-methanol-choline oxidoreductase family.
Organizational Affiliation: 
Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, University of Fukui.