NADPH-cytochrome c (P-450) reductase has the activity of NADPH-linked aquacobalamin reductase in rat liver microsomes.
To elucidate the mammalian system for synthesis of cobalamin coenzymes, microsomal NADPH-linked aquacobalamin reductase was purified and characterized. The enzyme was purified about 534-fold over rat liver microsomal fraction in a yield of about 32%. The purified enzyme was homogeneous in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and had a monomeric molecular weight of 79,000. The purified aquacobalamin reductase showed a high specific activity (about 55 mumol/min per mg protein) of NADPH-cytochrome c (P-450) reductase. About 33% of the NADPH-cytochrome c reductase activity found in the microsomal fraction was recovered in the final purified preparation. The activity ratio of NADPH-cytochrome c reductase/NADPH-linked aquacobalamin reductase was about 5.0 through the purification steps, indicating that the rat liver microsomal NADPH-linked aquacobalamin reductase is the NADPH-cytochrome c reductase.
Watanabe
F
F
Laboratory of Nutrition and Food Science, Hagoromo-gakuen College, Osaka, Japan.
Nakano
Y
Y
Saido
H
H
Tamura
Y
Y
Yamanaka
H
H
D000818:Animals; D006863:Hydrogen-Ion Concentration; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D008930:Mitochondria, Liver / Q000201:enzymology; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D009251:NADPH-Ferrihemoprotein Reductase / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013696:Temperature
C053436:aquacobalamin reductase (NADPH); D009247:NADH, NADPH Oxidoreductases; D009251:NADPH-Ferrihemoprotein Reductase