Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mitochondrial NADPH-linked aquacobalamin reductase was purified and characterized to clarify its enzymatic properties. The enzyme was purified about 360-fold over rat liver mitochondrial membranes in a yield of 7.5%. The purified enzyme was homogenous in SDS-PAGE. The molecular mass (M(r)) of the enzyme was calculated to be 65 kDa by SDS-PAGE and by Toyopearl HW55 gel filtration, indicating that the enzyme is a monomeric polypeptide with M(r) of 65 kDa. The enzyme was a flavoprotein containing 1 mol of FAD and FMN per mole of the enzyme. The enzyme was specific for NADPH as electron donor and had the ability to reduce cytochrome c (15.4 mumol.min-1 x mg protein-1), potassium ferricyanide (4.9 mumol.min-1 x mg protein-1) and 2,6-dichlorophenolindophenol (16.8 mumol.min-1.mg protein-1) as well as aquacobalamin (6.4 mumol.min-1 x mg protein-1). Although the enzyme immunoreacted with an antibody against NADPH-cytochrome P-450 reductase, which had the activity of the NADPH-linked aquacobalamin reductase in rat liver microsomes, the mitochondrial enzyme and the microsomal enzyme had different enzymological properties.
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PMID:Mitochondrial NADPH-linked aquacobalamin reductase is distinct from the NADPH-linked enzyme from microsomal membranes in rat liver. 822 2

Aquacobalamin reductase (NADPH), which catalyzes the reduction of aquacobalamin to cob(II)alamin in the synthesis of cobalamin coenzymes, has already been purified from mitochondria of Euglena gracilis and partly characterized. Here, the enzyme was further characterized to clarify its enzymatic properties. The enzyme reduced 2 mol of aquacobalamin per mole of NADPH and had NADPH diaphorase-like activity. The 16 amino acid residues at the NH2-terminal of the enzyme were identical with those of the NADPH diaphorase domain of pyruvate: NADP+ oxidoreductase, which is involved in Euglena wax ester fermentation. Peptide mapping of the aquacobalamin reductase showed that elution during C-18 reversed-phase high-performance liquid chromatography was identical to that of the NADPH diaphorase domain. Immunoblotting indicated that the Euglena aquacobalamin reductase had a higher molecular weight (166,000) in the intact mitochondria than the purified enzyme (65,000), and that the molecular weights of the native and purified enzyme were identical with those of the subunit and the NADPH diaphorase domain, respectively. These results showed that the aquacobalamin reductase isolated earlier was the NADPH diaphorase domain, cleaved by trypsin during preparation of the mitochondrial homogenate from the native enzyme. Purified pyruvate:NADP+ oxidoreductase also had the activity of aquacobalamin reductase, which suggests that the enzyme in Euglena mitochondria has more than one function in the synthesis of cobalamin co-enzymes.
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PMID:Characterization of aquacobalamin reductase (NADPH) from Euglena gracilis. 837 79