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B6db references: 85122796

type Journal Article
authors Singh, N. K.; Datta, K.
title Purification and characterization of rat kidney L-alanine: 4,5- dioxovalerate transaminase and inhibition by hemin
journal Biochim Biophys Acta
ui 85122796
year (1985)
volume 827
number 3
pages 305-9.
keywords Animal
abstract Rat kidney L-alanine:4,5-dioxovalerate transaminase (EC, 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 degrees 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, delta-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.
last changed 2002/11/12 16:17

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