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首页> 外文期刊>Bioscience Reports >Substrate specificity and structure of human aminoadipate aminotransferase/kynurenine aminotransferase II
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Substrate specificity and structure of human aminoadipate aminotransferase/kynurenine aminotransferase II

机译：人氨基己二酸氨基转移酶/犬尿氨酸氨基转移酶II的底物特异性和结构

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摘要

KAT (kynurenine aminotransferase) II is a primary enzyme in the brain for catalysing the transamination of kynurenine to KYNA (kynurenic acid). KYNA is the only known endogenous antagonist of the /V-methyl-D-aspartate receptor. The enzyme also catalyses the transamination of aminoadipate to a-oxoadipate; therefore it was initially named AADAT (aminoadipate aminotransferase). As an endotoxin, aminoadipate influences various elements of glutamatergic neurotransmission and kills primary astrocytes in the brain. A number of studies dealing with the biochemical and functional characteristics of this enzyme exist in the literature, but a systematic assessment of KAT II addressing its substrate profile and kinetic properties has not been performed. The present study examines the biochemical and structural characterization of a human KAT 11/AADAT Substrate screening of human KAT II revealed that the enzyme has a very broad substrate specificity, is capable of catalysing the transamination of 16 out of 24 tested amino acids and could utilize all 16 tested a-oxo acids as amino-group acceptors. Kinetic analysis of human KAT II demonstrated its catalytic efficiency for individual amino-group donors and acceptors, providing information as to its preferred substrate affinity. Structural analysis of the human KAT II complex with a-oxoglutaric acid revealed a conformational change of an N-terminal fraction, residues 15-33, that is able to adapt to different substrate sizes, which provides a structural basis for its broad substrate specificity.
机译：KAT（犬尿氨酸氨基转移酶）II是大脑中的一种主要酶，用于催化犬尿氨酸向KYNA（犬尿酸）的氨基转移。 KYNA是/ V-甲基-D-天冬氨酸受体的唯一已知内源性拮抗剂。该酶还催化氨基己二酸酯向α-氧代己二酸酯的氨基转移。因此，它最初被称为AADAT（氨基己二酸氨基转移酶）。氨基己二酸酯作为一种内毒素会影响谷氨酸能神经传递的各种元素，并杀死大脑中的原代星形胶质细胞。关于该酶的生化和功能特性的许多研究已有文献报道，但尚未进行针对其底物谱和动力学性质的KAT II的系统评价。本研究检查了人KAT 11 / AADAT的生化和结构特征。对人KAT II的底物筛选显示该酶具有非常广泛的底物特异性，能够催化24种测试氨基酸中的16种进行氨基转移，并可以利用所有16种经测试的α-氧代酸均作为氨基受体。人KAT II的动力学分析表明其对单个氨基供体和受体的催化效率，提供了有关其优选底物亲和力的信息。用α-氧代戊二酸对人KAT II复合物的结构分析显示，N末端级分（残基15-33）的构象变化能够适应不同的底物大小，这为其广泛的底物特异性提供了结构基础。

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