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：1971
卷号：68
期号：12
页码：2903-2907
DOI：10.1073/pnas.68.12.2903
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A mutant of Salmonella typhimurium LT-2 that requires either vitamin B6 or histidine for growth was found to synthesize vitamin B5 in amounts comparable to the parent strain, but to be deficient in imidazoleacetol phosphate transaminase (L-histidinolphosphate: 2-oxoglutarate aminotransferase, EC 2.6.1.9 ), an enzyme required for histidine biosynthesis. The mutant apotransaminase required a 50-fold higher concentration of pyridoxal 5'-phosphate for half-maximum activation than the corresponding wild-type enzyme; the fully activated mutant enzyme also displays a much lower maximum rate of catalysis than the enzyme from the parent strain. Such mutational changes in bacteria resemble those in certain vitamin B6-responsive genetic diseases in man and provide useful experimental material for the study of factors involved in coenzyme binding and enzymatic catalysis.
