STEREOCHEMISTRY OF AN ALPHA,BETA-ELIMINATION REACTION BY D-GLUCOSAMINATE DEHYDRATASE
STEREOCHEMISTRY OF AN ALPHA,BETA-ELIMINATION REACTION BY D-GLUCOSAMINATE DEHYDRATASE
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DOI：
10.1016/0014-5793(83)80242-7
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发表时间：
1983-01-01
期刊：
影响因子：
3.5
通讯作者：
SODA, K
中科院分区：
文献类型：
--
作者：
IWAMOTO, R;IMANAGA, Y;SODA, K
D2O 中 D-葡萄糖胺脱水酶反应的质子 NMR 分析表明，在产物 2-酮-3-脱氧-D-葡萄糖酸盐的 C-3 碳上掺入了一个氘原子。基于产物的C-3质子的化学位移以及2C5吡喃糖构象中C-3和C-4轴-轴耦合的耦合常数特征，氘处于亲S位置。因此，D-葡萄糖胺通过酶的脱水在C-3碳处以保留模式进行。动力学参数表明，速率决定步骤是从底物中提取 α-质子。
The proton NMR analysis of D-glucosaminate dehydratase reaction in D2O revealed the incorporation of a deuterium atom at C-3 carbon of the product, 2-keto-3-deoxy-D-gluconate. Based on the chemical shift of C-3 proton of the product and the coupling constant characteristic for the C-3 and C-4 axial-axial coupling in the2C5pyranose conformation, the deuterium is in the pro-S position. Thus, the dehydration of D-glucosaminate by the enzyme proceeds in a retention mode at C-3 carbon. Kinetic parameters show that the rate-determining step is the abstraction of α-proton from the substrate.