Appl Environ Microbiol. 1995 Oct;61(10):3729-33. doi: 10.1128/aem.61.10.3729-3733.1995.
A NAD-dependent secondary alcohol dehydrogenase has been purified from the alkane-degrading bacterium, Rhodococcus erythropolis ATCC 4277. The enzyme was found to be active against a broad range of substrates, particularly long-chain secondary aliphatic alcohols. Although optimal activity was observed with linear 2-alcohols containing between 6 and 11 carbon atoms, secondary alcohols as long as 2-tetradecanol were oxidized at 25% of the rate seen with mid-range alcohols. The purified enzyme was specific for the S-(+) stereoisomer of 2-octanol and had a specific activity for 2-octanol of over 200 (mu)mol/min/mg of protein at pH 9 and 37(deg)C, 25-fold higher than that of any previously reported S-(+) secondary alcohol dehydrogenase. Linear primary alcohols containing between 3 and 13 carbon atoms were utilized 20- to 40-fold less efficiently than the corresponding secondary alcohols. The apparent K(infm) value for NAD(sup+) with 2-octanol as the substrate was 260 (mu)M, whereas the apparent K(infm) values for the 2-alcohols ranged from over 5 mM for 2-pentanol to less than 2 (mu)M for 2-tetradecanol. The enzyme showed moderate thermostability (half-life of 4 h at 60(deg)C) and could potentially be useful for the synthesis of optically pure stereoisomers of secondary alcohols.
一种依赖 NAD 的仲醇脱氢酶已从烷烃降解细菌红球菌 Rhodococcus erythropolis ATCC 4277 中纯化出来。该酶对广泛的底物表现出活性，特别是长链仲脂肪醇。尽管观察到最佳活性的线性 2-醇含有 6 到 11 个碳原子，但最长可达 2-十四醇的仲醇的氧化速度仅为中链醇的 25%。纯化的酶对 2-辛醇的 S-(+)对映异构体具有特异性，在 pH 9 和 37°C 下，2-辛醇的比活性超过 200(mu)mol/min/mg 蛋白，比任何以前报道的 S-(+)仲醇脱氢酶高 25 倍。含 3 到 13 个碳原子的线性伯醇的利用率比相应的仲醇低 20 到 40 倍。以 2-辛醇为底物时，NAD+(sup+)的表观 K(infm)值为 260(mu)M，而 2-醇的表观 K(infm)值范围从 2-戊醇的超过 5 mM 到 2-十四醇的小于 2(mu)M。该酶显示出中等的热稳定性（在 60°C 下半衰期为 4 小时），并且可能对合成光学纯的仲醇对映异构体有用。
