Chen J S
Department of Biochemistry and Anaerobic Microbiology, Virginia Polytechnic Institute and State University, Blacksburg 24061-0305, USA.
FEMS Microbiol Rev. 1995 Oct;17(3):263-73. doi: 10.1111/j.1574-6976.1995.tb00210.x.
Alcohol dehydrogenase (ADH) is a key enzyme for the production of butanol, ethanol, and isopropanol by the solvent-producing clostridia. Initial studies of ADH in extracts of several strains of Clostridium acetobutylicum and C. beijerinckii gave conflicting molecular properties. A more coherent picture has emerged because of the following results: (i) identification of ADHs with different coenzyme specificities in these species; (ii) discovery of structurally conserved ADHs (type 3) in three solvent-producing species; (iii) isolation of mutants with deficiencies in butanol production and restoration of butanol production with a cloned alcohol/aldehyde dehydrogenase gene; and (iv) resolution of various 'C. acetobutylicum' cultures into four species. The three ADH isozymes of C. beijerinckii NRRL B592 have high sequence similarities to ADH-1 of Clostridium sp. NCP 262 (formerly C. acetobutylicum P262) and to the ADH domain of the alcohol/aldehyde dehydrogenase of C. acetobutylicum ATCC 824/DSM 792. The NADH-dependent activity of the ADHs from C. beijerinckii NRRL B592 and the BDHs from C. acetobutylicum ATCC 824 is profoundly affected by the pH of the assay, and the relative importance of NADH and NADPH to butanol production may be misappraised when NAD(P)H-dependent activities were measured at different pH values. The primary/secondary ADH of isopropanol-producing C. beijerinckii is a type-1 enzyme and is highly conserved in Thermoanaerobacter brockii (formerly Thermoanaerobium brockii) and Entamoeba histolytica. Several solvent-forming enzymes (primary ADH, aldehyde dehydrogenase, and 3-hydroxybutyryl-CoA dehydrogenase) are very similar between C. beijerinckii and the species represented by Clostridium sp. NCP 262 and NRRL B643. The realization of such relationships will facilitate the elucidation of the roles of different ADHs because each type of ADH can now be studied in an organism most amenable to experimental manipulations.
乙醇脱氢酶（ADH）是产溶剂梭菌生产丁醇、乙醇和异丙醇的关键酶。对丙酮丁醇梭菌和拜氏梭菌几个菌株提取物中的ADH进行的初步研究得出了相互矛盾的分子特性。由于以下结果，一幅更连贯的图景浮现出来：（i）在这些物种中鉴定出具有不同辅酶特异性的ADH；（ii）在三种产溶剂物种中发现结构保守的ADH（3型）；（iii）分离出丁醇生产有缺陷的突变体，并通过克隆的醇/醛脱氢酶基因恢复丁醇生产；（iv）将各种“丙酮丁醇梭菌”培养物解析为四个物种。拜氏梭菌NRRL B592的三种ADH同工酶与梭菌属NCP 262（以前的丙酮丁醇梭菌P262）的ADH-1以及丙酮丁醇梭菌ATCC 824/DSM 792的醇/醛脱氢酶的ADH结构域具有高度的序列相似性。拜氏梭菌NRRL B592的ADH的NADH依赖性活性以及丙酮丁醇梭菌ATCC 824的BDH的活性受到测定pH值的深刻影响，当在不同pH值下测量NAD（P）H依赖性活性时，NADH和NADPH对丁醇生产的相对重要性可能会被错误评估。产异丙醇的拜氏梭菌的初级/次级ADH是一种1型酶，在布氏嗜热厌氧菌（以前的布氏嗜热厌氧杆菌）和溶组织内阿米巴中高度保守。拜氏梭菌与由梭菌属NCP 262和NRRL B643代表的物种之间的几种产溶剂酶（初级ADH、醛脱氢酶和3-羟基丁酰辅酶A脱氢酶）非常相似。认识到这些关系将有助于阐明不同ADH的作用，因为现在可以在最适合进行实验操作的生物体中研究每种类型的ADH。
