Obrig T G, Gottlieb D
J Bacteriol. 1970 Mar;101(3):755-62. doi: 10.1128/jb.101.3.755-762.1970.
A study was made of the ability of cell-free protein synthesis systems from vegetative cells of different age of the fungus Rhizoctonia solani to produce polyphenylalanine. Polyuridylic acid-directed phenylalanine incorporation into peptides decreased linearly with cell age. The 105,000 x g supernatant fluid and ribosomal fractions were equally responsible for the total loss of synthetic activity of the older cells. Initial rates of phenylalanyl-transfer ribonucleic acid (tRNA) synthetase activity decreased with increasing cell age, which accounted for the defect of the supernatant fraction. An accelerated degradation of soluble phenylalanyl-RNA was associated with the ribosomes of the older cells. In vitro systems from cells of different age transferred phenylalanine from phenylalanyl-tRNA to polyphenylalanine at similar rates. Of the 15 specific aminoacyl-tRNA synthetases assayed, 5 increased and 5 decreased in specific activity with increased age; 3 others did not change during aging and 2 were below acceptable detectable levels.
对来自不同菌龄的立枯丝核菌营养细胞的无细胞蛋白质合成系统产生多聚苯丙氨酸的能力进行了研究。聚尿苷酸指导的苯丙氨酸掺入肽的量随细胞菌龄呈线性下降。105,000×g 上清液和核糖体组分对老龄细胞合成活性的总丧失负有同等责任。苯丙氨酰 - 转移核糖核酸（tRNA）合成酶的初始活性速率随细胞菌龄增加而降低，这解释了上清液组分的缺陷。可溶性苯丙氨酰 - RNA 的加速降解与老龄细胞的核糖体有关。来自不同菌龄细胞的体外系统以相似的速率将苯丙氨酸从苯丙氨酰 - tRNA 转移至多聚苯丙氨酸。在所检测的 15 种特异性氨酰 - tRNA 合成酶中，5 种酶的比活性随菌龄增加而升高，5 种酶的比活性随菌龄增加而降低；另外 3 种酶在老化过程中没有变化，2 种酶低于可接受的检测水平。
