[Phosphorylation reactions of lysyl-tRNA-synthetase from rat liver]. / Izuchenie reaktsii fosforilirovaniia lizil-tRNK-sintetazy iz pecheni krys.

The phosphorylation reaction of lysyl-tRNA-synthetase from the rat liver tissue was studied in the in vivo experiments. The activity of 3':5'-AMP-dependent protein kinase from the myocardium in the phosphorylation reaction is 3.4 times lower than that of the enzyme from the liver. Optimum conditions of the lysyl-tRNA-synthetase phosphorylation reaction were determined. The Vmax and Km values for the reaction were 2.7 pmol of 32P/mg per 1 minute and 0.4-10(-4), respectively. The lysyl-tRNA-synthetase phosphorylation increases the tRNA aminoacylation.

[Phosphorylation of aminoacyl-tRNA synthetase preparations of rat liver tissues in vivo and in vitro]. / Fosforilirovanie preparatov aminoatsil-tRNK-sintetaz tkani pecheni krys v opytakh in vivo and in vitro.

The capacity for phosphorylation was studied in aminoacyl-tRNA synthetases isolated from the rat liver after introducing Na2H32PO4 to the organism as well as in the in vitro experiments. Some kinetic characteristics of this reaction were investigated. The velocity of the aminoacyl-tRNA synthetases phosphorylation reaches its maximum 5 minutes later, and the enzyme saturation with substrate occurs at low concentration of the latter. The values of Km, Vmax and V0 are 1.27 x 10(-2) mg/ml, 8.33 mumol 32P/mg per 1 min and 6.09 mumol 32P/mg per 1 min, respectively. A conclusion is drawn that in the in vivo and in vitro experiments there occurs phosphorylation of the total preparation of aminoacyl-tRNA synthetases and individual lysyl-tRNA synthetase.