Controlling reaction specificity in pyridoxal phosphate enzymes.
Controlling reaction specificity in pyridoxal phosphate enzymes.
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DOI：
10.1016/j.bbapap.2011.05.019
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发表时间：
2011-11
期刊：
影响因子：
--
通讯作者：
Toney MD
中科院分区：
文献类型：
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作者：
Toney MD
吡哆醛5 '-磷酸酶普遍存在于所有生物的氮代谢中。它们催化各种各样的反应，包括外消旋、转氨、脱羧、消除、逆羟醛裂解、克莱森缩合等，最常见的是在含有氨基的底物上的α-氨基酸。由PLP酶催化的各种各样的反应是通过在底物和PLP之间形成的共价醛亚胺中间体稳定底物的Cα处的碳负离子中间体的能力实现的。本文综述了PLP酶的反应特异性的机制，重点介绍了这些反应的三个方面：立体电子效应、外部醛亚胺中间体的质子化状态以及碳负离子中间体与活性位点中蛋白质侧链的相互作用。
Pyridoxal 5'-phosphate enzymes are ubiquitous in the nitrogen metabolism of all organisms. They catalyze a wide variety of reactions including racemization, transamination, decarboxylation, elimination, retro-aldol cleavage, Claisen condensation, and others on substrates containing an amino group, most commonly α-amino acids. The wide variety of reactions catalyzed by PLP enzymes is enabled by the ability of the covalent aldimine intermediate formed between substrate and PLP to stabilize carbanionic intermediates at Cα of the substrate. This review attempts to summarize the mechanisms by which reaction specificity can be achieved in PLP enzymes by focusing on three aspects of these reactions: stereoelectronic effects, protonation state of the external aldimine intermediate, and interaction of the carbanionic intermediate with the protein side chains present in the active site.