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：1987
卷号：84
期号：15
页码：5207-5210
DOI：10.1073/pnas.84.15.5207
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Comparison of the amino acid sequence of Bacillus subtilis threonine synthase with the National Biomedical Research Foundation protein sequence library revealed a statistically significant extent of similarity between the sequence of the tryptophan synthase beta chain from various organisms and that of threonine synthase. This homology in the primary structure of threonine synthase and tryptophan synthase beta chain, which catalyze the last step in the threonine and the tryptophan biosynthetic pathways, respectively, correlates well with some of their catalytic properties and indicates that they have evolved from a common ancestor. The evolutionary relationship between these enzymes supports the hypothesis that primitive enzymes possessed a broad substrate specificity and were active in several metabolic pathways.
