标题：Nucleotide Sequence Divergence in the α-Chain-Structural Genes of Tryptophan Synthetase from Escherichia coli, Salmonella typhimurium, and Aerobacter aerogenes
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1973
卷号：70
期号：4
页码：1112-1116
DOI：10.1073/pnas.70.4.1112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Two different estimates were obtained for the extent of nucleotide sequence divergence in the structural genes of the tryptophan synthetase [α]-chains of Escherichia coli, Salmonella typhimurium, and Aerobacter aerogenes. One estimate was based on comparisons of the amino acid sequences of the respective [α] chains. The other was derived from measurements of the thermal stability of RNA-DNA hybrids formed with phage DNA carrying the [α]-chain structural gene of E. coli and labeled messenger RNA from the three bacterial species. Comparison of the two estimates suggests that during the course of evolution synonymous codon changes have accumulated in the [α]-chain-structural genes.
