Subcellular distribution and properties of rabbit liver aminoacyl-tRNA synthetases under myocardial ischemia |
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Authors: | Leonid L. Ivanov Zenius Martinkus Ol'ga V. Kharchenko Sana Sara Leonardas Lukoshevichius Antanas Prashkevichius Anna V. El'skaya |
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Affiliation: | (1) Department of Biochemistry, Kaunas Medical Academy, Z. Janushkevichiaus 4, 3009 Kaunas, Lithuania;(2) Institute of Molecular Biology and Genetics, Ukrainian Academy of Sciences, 252627 Kiev, Ukraine |
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Abstract: | Subcellular distribution of aminoacyl-tRNA synthetase activities has been studied in normal rabbit liver and under experimental myocardial ischemia (EMI). An increase in the activity of a number of aminoacyl-tRNA synthetases in postmitochondrial and postribosomal supernatants from rabbit liver has been determined 12 hr after EMI. Gel chromatography of the postribosomal supernatant on Sepharose 6B shows that aminoacyl-tRNA synthetase activities are distributed among the fractions with Mr 1.82×106, 0.84×106 (high-Mr aminoacyl-tRNA synthetase complexes) and 0.12–0.35×106. In the case of EMI aminoacyl-tRNA synthetase activities are partly redistributed from the 1.82×106 complex into the 0.84×106 complex. The catalytic properties of both free and complex leucyl-tRNA synthetases have been compared. KM for all the substrates are the values of the same order in norm and under EMI. A decrease in some aminoacyl-tRNA synthetase activities associated with polyribosomes has been observed 12 hr after EMI. The interaction of aminoacyl-tRNA synthetases with polyribosomes stimulates the catalytic activity of some enzymes and protects them from heat inactivationin vitro. It is assumed that the changes in association of aminoacyl-tRNA synthetases with high-Mr complexes and compartmentalization of these enzymes on polyribosomes may be related to the alteration of protein biosynthesis under myocardial ischemia. |
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Keywords: | aminoacyl-tRNA synthetase high-Mr complex protein biosynthesis rabbit liver myocardial ischemia |
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