Mitochondrial phenylalanyl t-RNA synthetase from yeast: formation of enzyme-substrate complexes shown by heat or SH reagent inactivation

The binding of substrates to purified mitochondrial phenylalanyl-tRNA synthetase from yeast was examined using the kinetics of heat or p-hydroxymercurybenzoate inactivation. Individually magnesium chloride and each of the substrates protect the enzyme against thermal denaturation and p-hydroxymercur...

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Bibliographic Details
Published in:	Biochimie Vol. 65; no. 6; p. 355
Main Authors:	Diatewa, M, Stahl, A J
Format:	Journal Article
Language:	English
Published:	France 01-06-1983
Subjects:	Amino Acyl-tRNA Synthetases - metabolism Hot Temperature Hydroxymercuribenzoates - pharmacology Iodoacetates - pharmacology Iodoacetic Acid Kinetics Mitochondria - enzymology Phenylalanine-tRNA Ligase - antagonists & inhibitors Phenylalanine-tRNA Ligase - metabolism Protein Denaturation Saccharomyces cerevisiae - enzymology Sulfhydryl Reagents Temperature
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Summary:	The binding of substrates to purified mitochondrial phenylalanyl-tRNA synthetase from yeast was examined using the kinetics of heat or p-hydroxymercurybenzoate inactivation. Individually magnesium chloride and each of the substrates protect the enzyme against thermal denaturation and p-hydroxymercurybenzoate inhibition. No enzyme protection is observed with ATP alone against p-hydroxymercurybenzoate inhibition. The combinations of the various substrates induce a synergistic protection effect. Protection constants of 31 microM and 0.3 microM were found for L-Phe and mt tRNAPhe respectively, from heat inactivation studies. The inhibition of the enzyme activity by p-hydroxymercurybenzoate can be reverted by 2-mercaptoethanol or dithiothreitol.
ISSN:	0300-9084