This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fultz, P N Articles by Kemper, J Search for Related Content PubMed PubMed Citation Articles by Fultz, P N Articles by Kemper, J

Wild-type isopropylmalate isomerase in Salmonella typhimurium is composed of two different subunits.

ABSTRACT

The isopropylmalate isomerase in Salmonella typhimurium is the second enzyme specific for leucine biosynthesis. It is a complex enzyme composed of two subunits which are coded for by two genes of the leucine operon, leuC and leuD. The two polypeptides have been shown to copurify through successive ammonium sulfate fractionations and have been identified on sodium dodecyl sulfate-polyacrylamide gels as having molecular weights of 51,000 (leuC gene product) and 23,500 (leuD gene product). They have also been shown to be fairly stable, since in vitro complementation of cell-free extracts of leuC and leuD mutant strains was demonstrated, with only a 40% loss of activity 16 h after preparation of the extracts. The native isopropylmalate isomerase was shown to have a Km for its substrate alpha-isopropylmalate of 3 x 10(-4)M.

This article has been cited by other articles:

• Xu, H., Zhang, Y., Guo, X., Ren, S., Staempfli, A. A., Chiao, J., Jiang, W., Zhao, G. (2004). Isoleucine Biosynthesis in Leptospira interrogans Serotype lai Strain 56601 Proceeds via a Threonine-Independent Pathway. J. Bacteriol. 186: 5400-5409 [Abstract] [Full Text]