Aspartate aminotransferase catalyzed oxygen exchange with solvent from oxygen-18-enriched alpha-ketoglutarate: evidence for slow exchange of enzyme-bound water.
Aspartate aminotransferase catalyzed oxygen exchange with solvent from oxygen-18-enriched alpha-ketoglutarate: evidence for slow exchange of enzyme-bound water.
复制标题
天冬氨酸转氨酶催化氧与富含氧 18 的 α-酮戊二酸的溶剂进行氧交换：酶结合水缓慢交换的证据。
DOI：
10.1021/bi00435a030
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发表时间：
1989
期刊：
影响因子：
2.9
通讯作者：
Kirsch,JF
中科院分区：
文献类型：
--
作者：
McLeish,MJ;Julin,DA;Kirsch,JF
加州大学生物化学系，伯克利，加州94720接收于1988年10月12日摘要：通过跟踪富含180-羰基-酮戊二酸的180损失率以及L-谷氨酸形成率，研究了线粒体天冬氨酸转氨酶反应中酮亚胺（或酮亚胺+奎宁）中间体的分配。发现这些速率常数的比率在10 C下等于1，这意味着上述中间体相对于正向和反向反应面临相等的势垒。该分配比为1，与从反应的-氨基酸侧测量的分配比一起[Julin，D.一、Wiesinger，H.，托尼，M. D、& Kirsch，JF（1989）Biochemistry（precedingpaper in this issue）]表明，从酮亚胺（或酮亚胺+奎宁）形式的酶与溶剂交换α-酮戊二酸衍生的H215 O的速率常数与KCl的速率常数相当。
Department of Biochemistry, University of California, Berkeley, California 94720 Received October 12, 1988 abstract: Partitioning of the ketimine (or ketimine+ quinonoid) intermediate (s) in the mitochondrial aspartate aminotransferase reactions was investigated by following the rates of loss of 180 from carbon-yl-180-enriched-ketoglutarate together with the rate of L-glutamate formation. The ratio of these rate constants was found to equal 1 at 10 C, implying that the above intermediate (s) face (s) equal barriers with respect to the forward and reverse reactions. Thispartition ratio of 1 together with that measured from the-amino acid side of the reaction [Julin, D. A., Wiesinger, H., Toney, M. D., & Kirsch, JF (1989) Biochemistry (precedingpaper in this issue)] suggests that the rate constant for exchange of a-ketoglutarate-derived H2lsO from the ketimine (or ketimine+ quinonoid) form (s) of the enzyme with solvent is comparable with that for kCii.