Elimination of cooperativity in aspartate transcarbamylase by nitration of a single tyrosine residue.
Elimination of cooperativity in aspartate transcarbamylase by nitration of a single tyrosine residue.
复制标题
通过单个酪氨酸残基的硝化消除天冬氨酸转氨甲酰酶的协同作用。
DOI：
10.1073/pnas.75.6.2654
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发表时间：
1978
影响因子：
11.1
通讯作者：
W. Lipscomb
中科院分区：
文献类型：
--
作者：
S. Landfear;D. R. Evans;W. Lipscomb
在之前的一份报告中 [Landfear, S. M., Lipscomb, W. N. 和 Evans, D.R. (1978) J.Biol。化学。 253, 3988--3996]我们证明四硝基甲烷可用于硝酸化天冬氨酸转氨甲酰酶（氨基甲酰磷酸：L-天冬氨酸氨基甲酰转移酶，EC 2.1.3.2）中有限数量的酪氨酸残基；这种修饰消除了协同作用、反馈抑制和酶活性，并减少了反馈抑制剂三磷酸胞苷的结合。协同性比其他特性损失得更快，并且这种损失与单个酪氨酸残基的硝化相关。在本文中，我们描述了由一种类型（催化或调节）的硝化亚基和另一种类型的天然亚基构建的杂种的饱和动力学。我们得出的结论是，导致协同性丧失的修饰是在催化亚基上。含有这种修饰的胰蛋白酶肽已被分离和鉴定。
In a previous report [Landfear, S. M., Lipscomb, W. N. & Evans, D.R. (1978) J. Biol. Chem. 253, 3988--3996] we demonstrated that tetranitromethane can be employed to nitrate a limited number of tyrosine residues in aspartate transcarbamylase (carbamoylphosphate:L-aspartate carbamoyltransferase, EC 2.1.3.2); such modification eliminates cooperativity, feedback inhibition, and enzymatic activity, and reduces binding of the feedback inhibitor cytidine triphosphate. Cooperativity is lost more rapidly than other properties, and this loss correlates with the nitration of a single tyrosine residue. In this paper, we describe the saturation kinetics of hybrid species constructed from nitrated subunits of one type (either catalytic or regulatory) and native subunits of the other type. We conclude that the modification responsible for loss of cooperativity is on the catalytic subunit. The tryptic peptide containing this modification has been isolated and identified.