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Query: KEGG:D02011 (FAD)
 5,530 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Flavin-free cytochrome b5 reductase was reconstituted with 1-deazaflavin and 5-deazaflavin mononucleotides and dinucleotides. The 5-deazaenzyme functioned in transhydrogenation reactions but lacked electron transferase activity. The 1-deazaenzyme was fully competent for both input and output reactions. The flavin reduction rate was lowered about sevenfold upon N-1 substitution of FAD, but hydrogen abstraction from NADH remained the limiting step. Autoxidation of the reduced enzyme was more rapid than with the normal cofactor. Oxidation was accompanied by appearance of a transient blue-type semiquinone and superoxide ion production. Flavin-free apoflavodoxin was reconstituted with 1-deaza-1-carbaflavin mononucleotide (1-deaza-FMN). Its behaviour toward dithionite and oxygen was qualitatively highly similar to that of native flavodoxin. These observations contrast with the fact that apoflavocytochrome b2 could not be reconstituted with 1-deaza-FMN [Pompon. D. and Lederer, F. (1979) Eur. J. Biochem. 96. 571-579]. These results, as well as other data from the literature, are discussed in the light of existing hypotheses, which try to correlate flavin protein interactions and flavoprotein function.
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PMID:Reconstitution of liver NADH: cytochrome b5 oxidoreductase and of Desulfovibvio vulgaris flavodoxin with 1-carba-1-deazaflavin. 715 84

The behaviour of cytochrome b5 reductase holoenzyme and apoenzyme toward blue-dextran--Sepharose has been studied. Holoenzyme was adsorbed at low ionic strength and could be eluted with 100 microM NADH or NAD+. Flavin-free enzyme was even more strongly bound and could be eluted with 1 M NaCl, or 100 microM NADH + 10 microM FAD. Separately the cofactors were without effect. FMN was less effective than FAD. ADP and AMP eluted nothing. Cibacron blue F3GA was found to exert a mixed inhibition on NADH oxidation. Dye binding to holoenzyme elicited a characteristic red shift in its spectrum. Comparison of the difference spectrum amplitude at 680 and 585 nm showed the presence of a second binding mode at higher dye concentrations. These results point to the existence for cytochrome b5 reductase of two binding sites with high affinity for blue-dextran--Sepharose: the NADH binding site and flavin binding site. For the latter it is clear that isoalloxazine pocket must play a role in dye binding. Cytochrome b5 reductase is the second flavoenzyme which has been shown to have affinity for immobilized dye at the flavin site, the first one being flavocytochrome b2, and FMN-dependent enzyme [D. Pompon and F. Lederer (1978) Eur. J. Biochem. 90, 563--569].
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PMID:Binding of Cibacron blue F3GA to the flavin and NADH sites in cytochrome b5 reductase. 743 74