Hicks S E, Wallwork J C
J Nutr. 1987 Jul;117(7):1234-40. doi: 10.1093/jn/117.7.1234.
This study presents evidence for the direct involvement of zinc in the translation of polypeptide chains in rat liver. Cell-free systems consisting of polyribosomes and fractions, enriched with aminoacyl-tRNA synthetase for incorporation of amino acids into trichloroacetic acid-insoluble proteins, were prepared from livers of three populations of rats: 1) rats fed ad libitum a diet containing 25 ppm zinc; 2) rats fed a diet containing less than 1 ppm zinc; and 3) rats pair fed to the zinc-deficient group a diet containing 25 ppm zinc. Group 2 showed typical signs of zinc deficiency, including decreased bone zinc. The protein synthetic ability of systems isolated from zinc-deficient rats was considerably depressed, resulting in incorporation of 59-69% of the amino acids incorporated by systems from pair-fed rats and 54-59% of those incorporated by ad libitum-fed control animals. This effect was significant after only 14 d of the dietary regimen. Experiments performed by mixing polyribosomes and synthetase fractions from the different groups indicated that a defect is located in the synthetase fraction. Acylation of tRNA by the synthetase fraction also was assayed and found to be 69-90% of that in zinc-sufficient preparations. It is suggested that one or more of the aminoacyl-tRNA synthetase enzymes from the rat liver may be zinc dependent.
本研究提供了锌直接参与大鼠肝脏中多肽链翻译的证据。从三组大鼠的肝脏中制备了无细胞体系，该体系由多核糖体和富含氨酰 - tRNA合成酶的组分组成，用于将氨基酸掺入三氯乙酸不溶性蛋白质中：1）随意喂食含25 ppm锌饮食的大鼠；2）喂食含锌量低于1 ppm饮食的大鼠；3）与缺锌组配对喂食含25 ppm锌饮食的大鼠。第2组表现出典型的锌缺乏症状，包括骨锌含量降低。从缺锌大鼠分离的体系的蛋白质合成能力显著降低，导致掺入的氨基酸量为配对喂食大鼠体系的59 - 69%，随意喂食对照动物体系的54 - 59%。仅在饮食方案实施14天后，这种效应就很显著。通过混合不同组的多核糖体和合成酶组分进行的实验表明，缺陷位于合成酶组分中。还对合成酶组分催化tRNA的酰化作用进行了测定，发现其为锌充足制剂的69 - 90%。提示大鼠肝脏中的一种或多种氨酰 - tRNA合成酶可能依赖锌。
