Subcellular distribution and properties of rabbit liver aminoacyl-tRNA synthetases under myocardial ischemia.
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 M(r) 1.82 x 10(6), 0.84 x 10(6) (high-M(r) aminoacyl-tRNA synthetase complexes) and 0.12-0.35 x 10(6). In the case of EMI aminoacyl-tRNA synthetase activities are partly redistributed from the 1.82 x 10(6) complex into the 0.84 x 10(6) 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 inactivation in vitro. It is assumed that the changes in association of aminoacyl-tRNA synthetases with high-M(r) complexes and compartmentalization of these enzymes on polyribosomes may be related to the alteration of protein biosynthesis under myocardial ischemia.
Ivanov
L L
LL
Department of Biochemistry, Kaunas Medical Academy, Lithuania.
Martinkus
Z
Z
Kharchenko
O V
OV
Sara
S
S
Lukoshevichius
L
L
Prashkevichius
A
A
El'skaya
A V
AV
D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D000818:Animals; D002384:Catalysis; D006358:Hot Temperature; D007935:Leucine-tRNA Ligase / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology; D017202:Myocardial Ischemia / Q000201:enzymology*; D011817:Rabbits; D012270:Ribosomes / Q000201:enzymology; D013347:Subcellular Fractions / Q000201:enzymology*
D000604:Amino Acyl-tRNA Synthetases; D007935:Leucine-tRNA Ligase