Carbonyl reductase activity exhibited by pig testicular 20 beta-hydroxysteroid dehydrogenase.
The carbonyl reductase activity exhibited by pig testicular 20 beta-hydroxysteroid dehydrogenase (20 beta-HSD) was examined using a recombinant enzyme. Kinetic parameters were obtained for 48 carbonyl group-containing substrates, including aromatic aldehydes, aromatic ketones, cycloketones, quinones, aliphatic aldehydes and aliphatic ketones. 20 beta-HSD showed a high affinity towards quinones, such as 9,10-phenanthrenequinone, alpha-naphthoquinone and menadione (Km values of 4, 2 and 5 microM, respectively), and the substrate utilization efficiency (Vmax/Km) of the enzyme against these quinones was very high. Cyclohexanone and 2-methylcyclohexanone were also reduced with a high Vmax/Km value, but not cyclopentanone or 2-methylcyclopentanone. Various aromatic aldehydes and ketones including benzaldehyde- and acetophenone-derivatives were reduced by 20 beta-HSD. Especially, 4-nitrobenzaldehyde and 4-nitroacetophenone were reduced with high Vmax/Km values in the related compounds. The enzyme also reduced the pyridine-derivatives, 2-, 3-, and 4-benzoylpyridine, with the Vmax/Km value for 2-benzoylpyridine being the highest. 20 beta-HSD reduced aliphatic aldehydes and aliphatic ketones, but was more effective on the former. The correlation between the structure of carbonyl compounds and their substrate Vmax/Km is discussed.
Nakajin
S
S
Department of Biochemistry, Faculty of Pharmaceutical Sciences, Hoshi University, Tokyo, Japan.
Tamura
F
F
Takase
N
N
Toyoshima
S
S
D015089:20-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D008297:Male; D010088:Oxidoreductases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013552:Swine; D013737:Testis / Q000201:enzymology*
D011994:Recombinant Proteins; D010088:Oxidoreductases; D015089:20-Hydroxysteroid Dehydrogenases