Comparison of the Tryptophan Synthetase α Subunits of Several Species of Enterobacteriaceae

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Abstract
Creighton , T. E. (Stanford University, Stanford), D. R. Helinski, R. L. Somerville, and C. Yanofsky . Comparison of the tryptophan synthetase α subunits of several species of Enterobacteriaceae . J. Bacteriol. 91: 1819–1826. 1966.—The tryptophan synthetase α subunits of Escherichia coli K-12, E. coli B, Shigella dysenteriae, Salmonella typhimurium , and Aerobacter aerogenes have been purified and their structures compared. Each of these α subunits exhibits a sedimentation coefficient of about 2.7 S . Peptide patterns of trypsin plus chymotrypsin digests of the α subunits have indicated that all of the α subunits have peptide regions in common. The patterns of E. coli K-12, E. coli B, and S. dysenteriae α subunits appear to be nearly identical, whereas the α subunits from S. typhimurium and A. aerogenes differ from those of E. coli and from each other. It has also been shown that the E. coli structural gene for the α subunit is translated identically in E. coli and S. typhimurium .