Abstract
Imidazoleglycerol-phosphate dehydratase (EC 4.2.1.19) activity was detected in extracts of several monocotyledonous and dicotyledonous plants using a newly developed assay method. The enzyme was purified 114,000-fold (to apparent homogeneity) from wheat germ by five chromatographic steps. Its native relative molecular weight (Mr) was determined to be 600,000 to 670,000, and it consists of identical subunits of Mr 25,500. In wheat germ, the dehydratase, unlike those of prokaryotic origin, is not associated with histidinol phosphatase activity. The reaction product was identified as imidazoleacetol phosphate (IAP) by comparing it with synthetic IAP as an authentic reference. The Km value for imidazoleglycerol phosphate was 0.36 mM at the optimal pH of 6.6. The enzyme required a reducing agent, such as 2-mercaptoethanol or dithiothreitol, and Mn2+ for maximal activity. 3-Amino-1,2,4-triazole competitively inhibited the activity with a Ki value of 46 [mu]M. The purification of imidazoleglycerol-phosphate dehydratase from wheat germ and histidinol dehydrogenase from cabbage (A. Nagai, A. Scheidegger [1991] Arch Biochem Biophys 284: 127-132) suggests that at least the second half of the histidine biosynthesis in plants is identical to that in microorganisms.
Full Text
The Full Text of this article is available as a PDF (1.0 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- AMES B. N., GARRY B., HERZENBERG L. A. The genetic control of the enzymes of histidine biosynthesis in Salmonella typhimurium. J Gen Microbiol. 1960 Apr;22:369–378. doi: 10.1099/00221287-22-2-369. [DOI] [PubMed] [Google Scholar]
- AMES B. N., MITCHELL H. K. The biosynthesis of histidine; imidazoleglycerol phosphate, imidazoleacetol phosphate, and histidinol phosphate. J Biol Chem. 1955 Feb;212(2):687–696. [PubMed] [Google Scholar]
- AMES B. N. The biosynthesis of histidine; D-erythro-imidazoleglycerol phosphate dehydrase. J Biol Chem. 1957 Sep;228(1):131–143. [PubMed] [Google Scholar]
- Bradford M. M. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976 May 7;72:248–254. doi: 10.1006/abio.1976.9999. [DOI] [PubMed] [Google Scholar]
- Brady D. R., Houston L. L. Some properties of the catalytic sites of imidazoleglycerol phosphate dehydratase-histidinol phosphate phosphatase, a bifunctional enzyme from Salmonella typhimurium. J Biol Chem. 1973 Apr 10;248(7):2588–2592. [PubMed] [Google Scholar]
- DAVIS B. J. DISC ELECTROPHORESIS. II. METHOD AND APPLICATION TO HUMAN SERUM PROTEINS. Ann N Y Acad Sci. 1964 Dec 28;121:404–427. doi: 10.1111/j.1749-6632.1964.tb14213.x. [DOI] [PubMed] [Google Scholar]
- FINK G. R. GENE-ENZYME RELATIONS IN HISTIDINE BIOSYNTHESIS IN YEAST. Science. 1964 Oct 23;146(3643):525–527. doi: 10.1126/science.146.3643.525. [DOI] [PubMed] [Google Scholar]
- LOPER J. C., GRABNAR M., STAHL R. C., HARTMAN Z., HARTMAN P. E. GENES AND PROTEINS INVOLVED IN HISTIDINE BIOSYNTHESIS IN SALMONELLA. Brookhaven Symp Biol. 1964 Dec;17:15–52. [PubMed] [Google Scholar]
- Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
- Millay R. H., Jr, Houston L. L. Purification and properties of yeast histidinol phosphate phosphatase. Biochemistry. 1973 Jul 3;12(14):2591–2596. doi: 10.1021/bi00738a007. [DOI] [PubMed] [Google Scholar]
- Staples M. A., Houston L. L. Proteolytic degradation of imidazoleglycerolphosphate dehydratase-histidinol phosphatase from Salmonella typhimurium and the isolation of a resistant bifunctional core enzyme. J Biol Chem. 1979 Feb 25;254(4):1395–1401. [PubMed] [Google Scholar]