Cronholm T, Larsén C, Jvövall J, Theorell H, Akeson A
Acta Chem Scand B. 1975;29(5):571-6. doi: 10.3891/acta.chem.scand.29b-0571.
Alcohol dehydrogenase from horse (isoenzyme SS and ES, but not EE), rat and human liver were found to catalyze the NAD-dependent oxidation of 3beta-hydroxy groups in 5alpha- and 5beta-steroids of the C19, C21, and C24 series. The enzymes from horse and rat liver were more active on 5beta-than on 5alpha-steroids. This difference was most marked with the enzyme from rat liver, especially with 3beta-hydroxyandrostan-17-ones and 3beta-hydroxypregnan-20-ones as substrates. The Km of isoenzyme ES from horse liver was lower for 3beta-hydroxy-5alpha-cholanoic acid (0.4 muM) than for 3beta-hydroxy-5beta-cholanoic acid (0.9 muM). 3alpha-Hydroxysteroids were not substrates for the enzymes from horse and rat liver. Human liver alcohol dehydrogenase had low affinity for 3beta-hydroxy-5alpha (and 5beta)-cholanoic acids, but oxidation could be clearly demonstrated by gas chromatographic analysis of the products.
已发现来自马（同工酶SS和ES，但不是EE）、大鼠和人肝脏的乙醇脱氢酶可催化C19、C21和C24系列5α-和5β-甾体中3β-羟基的NAD依赖性氧化。来自马和大鼠肝脏的酶对5β-甾体的活性比对5α-甾体的活性更高。这种差异在大鼠肝脏的酶中最为明显，尤其是以3β-羟基雄甾烷-17-酮和3β-羟基孕烷-20-酮作为底物时。马肝脏同工酶ES对3β-羟基-5α-胆酸（0.4μM）的Km低于对3β-羟基-5β-胆酸（0.9μM）的Km。3α-羟基甾体不是来自马和大鼠肝脏的酶的底物。人肝脏乙醇脱氢酶对3β-羟基-5α（和5β）-胆酸的亲和力较低，但通过产物的气相色谱分析可以清楚地证明氧化作用。
