Chemical and Pharmaceutical Bulletin
Online ISSN : 1347-5223
Print ISSN : 0009-2363
ISSN-L : 0009-2363
Purification and Characterization of Befunolol Reductase from Rabbit Liver
Yorishige IMAMURAYoshihide NOZAKIMasaki OTAGIRI
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1989 Volume 37 Issue 12 Pages 3338-3342

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Abstract

An enzyme (befunolol reductase) which catalyzes the reduction of befunolol to dihydrobefunolol was purified from the cytosolic fraction of rabbit liver to homogeneity by various chromatographic techniques. Befunolol reductase had molecular weights of 29000 on sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis and 34000 on gel filtration. The enzyme required reduced nicotinamide adenine dinucleotide phosphate (NADPH) as a cofactor and showed an optimal pH of 6.5. The apparent Km and Vmax values of the enzyme for the reduction of befunolol were 1.7 mM and 4.4 units/mg, respectively. Flavonoids, sulfhydryl reagents, heavy metals and coumarins strongly inhibited the enzyme. The enzyme catalyzed the reduction of a variety of aromatic ketones. In addition to befunolol, some ketone-containing drugs such as daunorubicin and levobunolol were efficiently reduced by the enzyme. On the basis of substrate specificities for steroids, befunolol rductase purified from the cytosolic fraction of rabbit liver appeared to be a 3α-hydroxysteroid dehydrogenase.

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© The Pharmaceutical Society of Japan
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