Shaw J P, Harayama S
Département de Biochimie Médicale, Centre Médical Universitaire, Genève, Switzerland.
Eur J Biochem. 1990 Aug 17;191(3):705-14. doi: 10.1111/j.1432-1033.1990.tb19179.x.
Benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase, two enzymes of the xylene degradative pathway encoded by the plasmid TOL of a Gram-negative bacterium Pseudomonas putida, were purified and characterized. Benzyl alcohol dehydrogenase catalyses the oxidation of benzyl alcohol to benzaldehyde with the concomitant reduction of NAD+; the reaction is reversible. Benzaldehyde dehydrogenase catalyses the oxidation of benzaldehyde to benzoic acid with the concomitant reduction of NAD+; the reaction is irreversible. Benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase also catalyse the oxidation of many substituted benzyl alcohols and benzaldehydes, respectively, though they were not capable of oxidizing aliphatic alcohols and aldehydes. The apparent Km value of benzyl alcohol dehydrogenase for benzyl alcohol was 220 microM, while that of benzaldehyde dehydrogenase for benzaldehyde was 460 microM. Neither enzyme contained a prosthetic group such as FAD or FMN, and both enzymes were inactivated by SH-blocking agents such as N-ethylmaleimide. Both enzymes were dimers of identical subunits; the monomer of benzyl alcohol dehydrogenase has a mass of 42 kDa whereas that of the monomer of benzaldehyde dehydrogenase was 57 kDa. Both enzymes transfer hydride to the pro-R side of the prochiral C4 of the pyridine ring of NAD+.
苄醇脱氢酶和苯甲醛脱氢酶是由革兰氏阴性细菌恶臭假单胞菌的质粒TOL编码的二甲苯降解途径中的两种酶，对它们进行了纯化和特性鉴定。苄醇脱氢酶催化苄醇氧化为苯甲醛，同时使NAD⁺还原；该反应是可逆的。苯甲醛脱氢酶催化苯甲醛氧化为苯甲酸，同时使NAD⁺还原；该反应是不可逆的。苄醇脱氢酶和苯甲醛脱氢酶还分别催化许多取代苄醇和苯甲醛的氧化反应，不过它们不能氧化脂肪族醇和醛。苄醇脱氢酶对苄醇的表观Km值为220微摩尔，而苯甲醛脱氢酶对苯甲醛的表观Km值为460微摩尔。两种酶均不含有诸如FAD或FMN之类的辅基，并且两种酶都被诸如N - 乙基马来酰亚胺之类的SH - 阻断剂灭活。两种酶均为相同亚基的二聚体；苄醇脱氢酶的单体质量为42 kDa，而苯甲醛脱氢酶的单体质量为57 kDa。两种酶都将氢负离子转移到NAD⁺吡啶环前手性C4的前R侧。
