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. 1981 Oct;148(1):210–219. doi: 10.1128/jb.148.1.210-219.1981

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

P N Fultz, J Kemper
PMCID: PMC216183  PMID: 7026530

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.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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