Coenzyme A-acylating aldehyde dehydrogenase from Clostridium beijerinckii NRRL B592
Coenzyme A-acylating aldehyde dehydrogenase from Clostridium beijerinckii NRRL B592
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来自拜氏梭菌 NRRL B592 的辅酶 A-酰化醛脱氢酶
DOI：
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发表时间：
1990
影响因子：
4.4
通讯作者：
Jiann
中科院分区：
文献类型：
--
作者：
R. Yan;Jiann
乙醛和丁醛是产溶剂梭菌生产乙醇和1-丁醇过程中乙醇脱氢酶的底物。在厌氧条件下，从beijerinkii Clostridium NRRL B592中纯化出一种辅酶A (CoA)-酰化醛脱氢酶（ALDH），可将酰基辅酶A转化为醛和辅酶A。ALDH的天然分子量（Mr）为100,000，亚基Mr为55,000，表明ALDH为二聚体。纯化的ALDH不含醇脱氢酶活性。以乙醛和丁醛作为替代底物测量的活性被共纯化，表明相同的ALDH可以催化乙醇和丁醇生产的两种醛的形成。根据乙酰辅酶a和丁基辅酶a的Km和Vmax值，ALDH对丁醛的生成比乙醛更有效。ALDH可以使用NAD(H)或NADP(H)作为辅酶，但NAD(H)的Km远低于NADP(H)。动力学数据表明该反应是乒乓机制。ALDH在Tris缓冲液中比在磷酸盐缓冲液中更稳定。正向反应（生理方向；醛生成）的表观最适pH在6.5 ~ 7之间，反向反应（酰基-辅酶a生成）的表观最适pH在9.5以上。NAD(H)/NADP(H)连锁活性比值随ph的降低而升高。ALDH对O2敏感，但二硫苏糖醇可以保护ALDH不受O2失活。o2失活的酶可以在检测前用辅酶a在二硫苏糖醇存在或不存在的情况下重新激活。
Acetaldehyde and butyraldehyde are substrates for alcohol dehydrogenase in the production of ethanol and 1-butanol by solvent-producing clostridia. A coenzyme A (CoA)-acylating aldehyde dehydrogenase (ALDH), which also converts acyl-CoA to aldehyde and CoA, has been purified under anaerobic conditions from Clostridium beijerinckii NRRL B592. The ALDH showed a native molecular weight (Mr) of 100,000 and a subunit Mr of 55,000, suggesting that ALDH is dimeric. Purified ALDH contained no alcohol dehydrogenase activity. Activities measured with acetaldehyde and butyraldehyde as alternative substrates were copurified, indicating that the same ALDH can catalyze the formation of both aldehydes for ethanol and butanol production. Based on the Km and Vmax values for acetyl-CoA and butyryl-CoA, ALDH was more effective for the production of butyraldehyde than for acetaldehyde. ALDH could use either NAD(H) or NADP(H) as the coenzyme, but the Km for NAD(H) was much lower than that for NADP(H). Kinetic data suggest a ping-pong mechanism for the reaction. ALDH was more stable in Tris buffer than in phosphate buffer. The apparent optimum pH was between 6.5 and 7 for the forward reaction (the physiological direction; aldehyde forming), and it was 9.5 or higher for the reverse reaction (acyl-CoA forming). The ratio of NAD(H)/NADP(H)-linked activities increased with decreasing pH. ALDH was O2 sensitive, but it could be protected against O2 inactivation by dithiothreitol. The O2-inactivated enzyme could be reactivated by incubating the enzyme with CoA in the presence or absence of dithiothreitol prior to assay.
将钩口鱼子 (Trichogaster cosby) 中的脂肪酸还原为醇。
DOI：
10.1016/0005-2760(81)90228-9
发表时间：
1981
期刊：
Biochimica et biophysica acta
影响因子：
--
作者：
Griffith,TW;Sand,DM;Schlenk,H
通讯作者：
Schlenk,H