Domain Closure, Substrate Specificity and Catalysis of d-Lactate Dehydrogenase from Lactobacillus bulgaricus
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- 作者：Razeto ; Adelia ; Kochhar ; Sunil ; Hottinger ; Herbert ; Dauter ; Miroslava ; Wilson ; Keith S. ; Lamzin ; Victor S.
- 关键词：d-lactate dehydrogenase ; conformational asymmetry ; domain closure ; stereoselectivity ; substrate specificity ; DEPC ; diethylpyrocarbonate ; d-HicDH ; d-2-hydroxyisocaproate dehydrogenase ; d-LDH ; d-lactate dehydrogenase ; d-LDHb ; d-LDH from Lactobacillus bulgar
- 刊名：Journal of Molecular Biology
- 出版年：2002
- 出版时间：April 19, 2002
- 年：2002
- 卷：318
- 期：1
- 页码：109-119
- 全文大小：1.08 M
文摘
NAD-dependent Lactobacillus bulgaricus d-Lactate dehydrogenase (d-LDHb) catalyses the reversible conversion of pyruvate into d-lactate. Crystals of d-LDHb complexed with NADH were grown and X-ray data collected to 2.2Å. The structure of d-LDHb was solved by molecular replacement using the dimeric Lactobacillus helveticus d-LDH as a model and was refined to an R-factor of 20.7 % . The two subunits of the enzyme display strong asymmetry due to different crystal environments. The opening angles of the two catalytic domains with respect to the core coenzyme binding domains differ by 16°. Subunit A is in an “open” conformation typical for a dehydrogenase apo enzyme and subunit B is “closed”. The NADH-binding site in subunit A is only 30 % occupied, while in subunit B it is fully occupied and there is a sulphate ion in the substrate-binding pocket.