NADPH-dependence of vitamin B2-aldehyde-forming enzyme.

Vitamin B2-aldehyde-forming enzyme isolated from Schizophyllum commune with 1,400-fold purity was found to require NADPH under aerobic but not anaerobic conditions. Both NADPH- and DCIP-requiring enzyme activities which could not be separated by our enzyme purification system were found in the same single protein band on polyacrylamide disc gel electrophoresis. The cation, Cu2+, markedly stimulated the NADPH-dependent enzyme reaction under the aerobic conditions. The reagents, EDTA, pyrazole, N-ethylmaleimide, PCMB, and arsenite, inhibited the formation of vitamin B2-aldehyde to various extents, whereas azide did not.