大肠杆菌核糖体蛋白形成过程中链延伸的方向
Direction of chain elongation in the formation of Escherichia coli ribosomal protein.
作者信息
Iwata S, Kaji H
出版信息
Proc Natl Acad Sci U S A. 1971 Mar;68(3):690-4. doi: 10.1073/pnas.68.3.690.
Ribosomal proteins were isolated from logarithmically growing Escherichia coli cells given [(14)C]alanine for short periods. Surprisingly, the specific activity of alanine at the NH(2)-terminal end was higher than that of alanine released by carboxypeptidase A digestion of the ribosomal protein. To determine the direction of chain elongation more precisely, Escherichia coli cells were grown with [(3)H]amino acids, and [(14)C]amino acids were then given to the (3)H-labeled cells as a pulse. Radioactive 30S ribosomal proteins were isolated from these cells and subjected to carboxypeptidase digestion. The ratio of (14)C to (3)H of the released amino acids increased as the time for carboxypeptidase digestion progressed. These observations suggest that some of the ribosomal proteins may be synthesized from the carboxyl end to the amino end through a novel mechanism.
从对数生长期的大肠杆菌细胞中短时间给予[¹⁴C]丙氨酸后分离核糖体蛋白。令人惊讶的是，核糖体蛋白氨基末端丙氨酸的比活性高于羧肽酶A消化核糖体蛋白释放的丙氨酸的比活性。为了更精确地确定链延伸的方向，用[³H]氨基酸培养大肠杆菌细胞，然后将[¹⁴C]氨基酸作为脉冲给予³H标记的细胞。从这些细胞中分离出放射性30S核糖体蛋白并进行羧肽酶消化。随着羧肽酶消化时间的延长，释放氨基酸的¹⁴C与³H的比率增加。这些观察结果表明，一些核糖体蛋白可能通过一种新机制从羧基末端向氨基末端合成。
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