非泌乳期牛乳腺pH5酶对大鼠肝脏氨基酸掺入系统中蛋白质合成各阶段的抑制作用。

Inhibitory effects of pH5 enzyme from non-lactating bovine mammary gland on various stages of protein synthesis in the rat liver amino acid-incorporating system.

作者信息

Herrington M D, Hawtrey A O

出版信息

Biochem J. 1969 Dec;115(4):671-8. doi: 10.1042/bj1150671.

DOI:10.1042/bj1150671

PMID:5357016

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1185192/

Abstract

pH5 enzyme from non-lactating bovine mammary gland was found to contain potent inhibitors of protein synthesis in the rat liver cell-free system. These inhibitors affect (a) formation of aminoacyl-tRNA where tRNA represents transfer RNA, (b) transfer of labelled amino acids from rat liver amino[(14)C]acyl-tRNA to protein in rat liver polyribosomes, and (c) incorporation of (14)C-labelled amino acids into peptide by rat liver polyribosomes supplemented with rat liver pH5 enzyme. 2. Increasing amounts of pH5 enzyme from bovine mammary gland progressively inhibited the incorporation of labelled amino acids into protein by a complete incorporating system from rat liver. Approx. 80% inhibition was observed at a concentration of 2mg. of protein of pH5 enzyme from bovine mammary gland. The inhibitory effect of the bovine pH5 enzyme fraction could not be overcome by the addition of increasing amounts of rat liver pH5 enzyme. 3. Fractionation of bovine pH5 enzyme with ammonium sulphate into four fractions showed that all the fractions inhibited the incorporation of (14)C-labelled amino acids in the rat liver system, but to varying extents. The highest inhibition observed (90%) was exhibited by the 60%-saturated-ammonium sulphate fraction. 4. Heat treatment of bovine pH5 enzyme at various temperatures caused only a partial loss of its inhibitory effect on labelled amino acid incorporation by the rat liver system. Treatment at 105 degrees for 5min. resulted in the bovine pH5 enzyme fraction losing 30% of its inhibitory activity. 5. pH5 enzyme from bovine mammary gland strongly inhibited the charging of rat liver tRNA in the presence of its own pH5 enzymes. 6. The transfer of labelled amino acids from rat liver amino[(14)C]acyl-tRNA to protein in a system containing rat liver polyribosomes and pH5 enzyme was almost completely inhibited by bovine pH5 enzyme at a concentration of 2mg. of protein of the enzyme fraction. 7. One of the inhibitors of various stages of protein synthesis in rat liver present in bovine pH5 enzyme was identified as an active ribonuclease, and the second inhibitor present was shown to be tRNA.

摘要

发现来自非泌乳期牛乳腺的pH5酶在大鼠肝细胞无细胞体系中含有强效蛋白质合成抑制剂。这些抑制剂影响：（a）氨酰tRNA（其中tRNA代表转移RNA）的形成；（b）标记氨基酸从大鼠肝脏氨基[（14）C]酰tRNA转移至大鼠肝脏多核糖体中的蛋白质；（c）通过补充大鼠肝脏pH5酶的大鼠肝脏多核糖体将（14）C标记氨基酸掺入肽中。2. 来自牛乳腺的pH5酶量增加会逐渐抑制大鼠肝脏完整掺入体系将标记氨基酸掺入蛋白质。在牛乳腺pH5酶蛋白浓度为2mg时观察到约80%的抑制率。增加大鼠肝脏pH5酶的量并不能克服牛pH5酶组分的抑制作用。3. 用硫酸铵将牛pH5酶分级分离成四个组分，结果表明所有组分均抑制大鼠肝脏体系中（14）C标记氨基酸的掺入，但程度不同。观察到的最高抑制率（90%）由60%饱和度硫酸铵组分表现出来。4. 在不同温度下对牛pH5酶进行热处理，其对大鼠肝脏体系标记氨基酸掺入的抑制作用仅部分丧失。在105℃处理5分钟导致牛pH5酶组分丧失30%的抑制活性。5. 在其自身pH5酶存在的情况下，来自牛乳腺的pH5酶强烈抑制大鼠肝脏tRNA的氨酰化。6. 在含有大鼠肝脏多核糖体和pH5酶的体系中，当牛pH5酶组分蛋白浓度为2mg时，标记氨基酸从大鼠肝脏氨基[（14）C]酰tRNA转移至蛋白质的过程几乎被完全抑制。7. 牛pH5酶中存在的大鼠肝脏蛋白质合成各阶段的抑制剂之一被鉴定为活性核糖核酸酶，另一种存在的抑制剂被证明是tRNA。