Hönes J, Jany K D, Pfleiderer G, Wagner A F
FEBS Lett. 1987 Feb 23;212(2):193-8. doi: 10.1016/0014-5793(87)81343-1.
Based on homology of partial sequences, on physico-chemical evidence and on studies using chemical modification, we came to the tentative conclusion that tetrameric glucose dehydrogenases from Bacillus megaterium and B. subtilis should have a structure closely related to that of lactate dehydrogenase. The overall homology of primary structures was found to be very low, however, and independent predictions of secondary structure produced a clearly different pattern of beta-strands and alpha-helices. We nevertheless tried a manual prediction based on the hydrophobic nature of internal beta-sheet and on the amphiphilic character of external helices. This treatment led to the identification of analogues of all the beta-strands present in lactate dehydrogenase with the exception of beta C. Six amphiphilic helices were identified corresponding to alpha B, alpha C, alpha D, alpha 1F, alpha 2F and alpha 3G in lactate dehydrogenase. Conserved functional residues were found at analogous positions. The Q and R intersubunit contacts could be identified and partial proteolysis was found to occur on the outer surface of the tetramer. The structure was found to explain the better binding of NADP as compared to NAD+ and offered a rationalization of the role of the essential lysine at position 201.
基于部分序列的同源性、物理化学证据以及化学修饰研究，我们初步得出结论：巨大芽孢杆菌和枯草芽孢杆菌的四聚体葡萄糖脱氢酶的结构应与乳酸脱氢酶的结构密切相关。然而，发现一级结构的总体同源性非常低，并且对二级结构的独立预测产生了明显不同的β-链和α-螺旋模式。尽管如此，我们基于内部β-折叠的疏水性和外部螺旋的两亲性进行了人工预测。这种处理导致鉴定出乳酸脱氢酶中除βC之外的所有β-链的类似物。鉴定出六个两亲性螺旋，分别对应于乳酸脱氢酶中的αB、αC、αD、α1F、α2F和α3G。在类似位置发现了保守的功能残基。可以确定Q和R亚基间接触，并且发现四聚体的外表面发生部分蛋白水解。发现该结构解释了与NAD+相比NADP具有更好的结合，并为201位必需赖氨酸的作用提供了合理的解释。
