Rat liver polysome N alpha-acetyltransferase: substrate specificity.
Rat liver polysome N alpha-acetyltransferase: substrate specificity.
复制标题
大鼠肝多聚体 N α-乙酰转移酶：底物特异性。
DOI：
10.1021/bi00218a019
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发表时间：
1991
期刊：
影响因子：
2.9
通讯作者：
Bradshaw,RA
中科院分区：
文献类型：
--
作者：
Yamada,R;Bradshaw,RA
Ryo Yantada* 和Ralph A. Bradshaw* Department of Biological Chemistry，College of Medicine，University of加州，Irvine，加州92717接收日期：1990年6月29日;修订版摘要：1990年11月5日利用一系列人工合成和天然底物，对大鼠肝多核糖体A“-乙酰转移酶（NAT）的底物特异性进行了研究。末端序列和长度。通过用所有19种常见的氨基酸连续替换N-末端丝氨酸、倒数第二个酪氨酸和倒数第二个前丝氨酸来产生SYSGGLLL结构的肽家族，然后评估其与大鼠肝酶的反应性。仅修饰具有N-末端丝氨酸、丙氨酸、甲硫氨酸、亮氨酸和苯丙氨酸的肽。第二位的甘氨酸、赖氨酸、精氨酸、缬氨酸、异亮氨酸和色氨酸（具有N-末端丝氨酸）具有强烈的抑制作用，脯氨酸完全阻断修饰。第三位取代对NAT活性的影响较小，甘氨酸、天冬氨酸、谷氨酸和色氨酸的抑制作用最大（具有N-末端Ser-Tyr）。这些观察结果通常与原位修饰一致，尽管存在一些显著差异，特别是在氨基末端残基方面。最佳链长被确定为10-11个残基，其中结构为α-（G）n-LLL的合成肽或促肾上腺皮质激素（ACTH）序列的范围为8至39个残基。促肾上腺皮质激素肽通常被发现是比相应的合成的好几倍的底物。活性不受链长增加超过~ 17个残基的影响。这些数据支持这样的观点：多核糖体催化的N“-乙酰化作为长度约20-40个氨基酸的新生链上的共翻译事件发生。
Ryo Yantada* and Ralph A. Bradshaw* Department of Biological Chemistry, College of Medicine, University of California, Irvine, California 92717 Received June 29,¡ 990; Revised Manuscript Received November 5, 1990 abstract: The substrate specificity of polysome rat liver A “-acetyltransferase (NAT) has been examined by utilizing a series of synthetic and natural substrates that has been systematically altered with respect to N-terminal sequence and length. Families of peptides of the structure SYSGGLLL were generated by successively replacing the N-terminal serine, the penultimate tyrosine, and the antepenultimate serine with all 19 commonly occurring amino acids, which were then assessed for their reactivity with the rat liver enzyme. Only peptides with N-terminal serine, alanine, methionine, leucine, and phenylalanine were modified. Glycine, lysine, arginine, valine, isoleucine, and tryptophan in the second position are (with N-terminal serine) strongly inhibitory, and proline completely blocks modification. Third-position substitutions have less of an effect on NAT activity with glycine, aspartic acid, glutamic acid, and tryptophan being most inhibiting (with N-terminal Ser-Tyr). These observations are generally in agreement with in situ modifications although there are some significant differences particularly with respect to the amino-terminal residues. Optimal chain length was determined to be 10-11 residues with either synthetic peptides of the structure SYS-(G)„-LLL or adrenocorticotropin (ACTH) sequences ranging from 8 to 39 residues. The ACTH peptides were generally foundto be severalfold better substrates than the corresponding synthetic ones. Activity was not affected by increased chain length beyond~ 17 residues. These data support the view that polysome-catalyzed N “-acetylation occurs as a cotranslational event on nascent chains of about 20-40 amino acids in length.