Purification and characterization of rat kidney L-alanine: 4,5-dioxovalerate transaminase and inhibition by hemin

Singh, Nishi K. ; Datta, K. (1985) Purification and characterization of rat kidney L-alanine: 4,5-dioxovalerate transaminase and inhibition by hemin Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 827 (3). pp. 305-309. ISSN 0167-4838

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Official URL: http://linkinghub.elsevier.com/retrieve/pii/016748...

Related URL: http://dx.doi.org/10.1016/0167-4838(85)90215-8

Abstract

Rat kidney l-alanine:4,5-dioxovalerate transaminase (EC 2.6.1.43), which may be involved in the formation of aminolevulinic acid in mammalian cells, was purified 82-fold to apparent homogeneity with a 19% yield. Molecular weight of the enzyme, as estimated by gel filtration, was found to be 225 000. In polyacrylamide gel electrophoresis under denaturing conditions, the enzyme moved as a single band corresponding to an Mr of 37 000, suggesting that the enzyme is composed of six identical subunits. The Km values of l-alanine and 4,5-dioxovalerate are 2.9 and 0.25 mM, respectively. The enzyme had an optimum activity at pH 6.6 and was most active at 65°C. Among some amino acids tested, l-alanine proved to be the most efficient amino donor, and the enzyme was also stereospecific for the l-isomer. The effect of intermediate metabolites of heme biosynthesis, for example, δ-aminolevulinic acid, protoporphyrin, hemin and bilirubin has been studied on purified l-alanine: 4,5-dioxovalerate transaminase. Amongst these metabolites, hemin and protoporphyrin were found to be effective inhibitors.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:4,5-dioxovaleric Acid; L-alanine 4,5-dioxovaleric Transaminase; Hemin Inhibition; (Rat Kidney)
ID Code:9109
Deposited On:29 Oct 2010 11:36
Last Modified:28 May 2011 10:59

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