Fungal riboflavin 5'-hydroxymethyl dehydrogenase catalyzes formation of both the aldehyde (riboflavinal) and the acid (riboflavinoic acid).
The purified enzyme from Schizophyllum commune that readily catalyzes the oxidation of the 5'-hydroxymethyl function of riboflavin (vitamin B2) with a redox dye and O2 to form the 5'-aldehyde can more slowly further oxidize the 5'-aldehyde to the 5'-acid. Hence, the formation of these so-called 'schizoflavins' can be accounted for by the action of one enzyme.
Genes with increased transcript levels following harvest of the sporophore of Agaricus bisporus have multiple physiological roles
We screened a cDNA library generated from harvested and stored sporophores of Agaricus bisporus and identified 19 genes with higher transcript levels than at the time of harvest. Five of these genes had no detectable mRNA levels prior to detachment from the mycelium. Sequence analysis of ten clones revealed significant similarities to known genes, these code for proteins involved in polymer breakdown and metabolism, cell wall synthesis, stress tolerance, cytochrome P450 activity and DNA binding. The diversity of functions of these genes suggests the changes in the sporophore after harvest involve several different physiological processes.
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.