[Study of the properties of leucyl-tRNA synthetase from porcine myocardium in a normal state and in experimental ischemia]. / Izuchenie svoistv leitsil-tRNK-sintetazy iz miokarda svin'i v norme i pri éksperimentalnoi ishemii.

Catalytic properties and thermostability of leucyl-tRNA-synthetase were studied both in free form and in the form of high molecular complexes, isolated from pig myocardium under normal state and after 15 min and 30 min ischemia. Km values of free and associated forms of leucyl-tRNA-synthetase were similar either in normal state or after 15-30 min ischemia. Complex-formation protected the enzyme from thermic inactivation under normal and ischemic conditions. Reverse redistribution of the leucyl-tRNA-synthetase activity was found in the fractions of free enzyme and high molecular complex depending on duration of ischemia.

[Study of the supramolecular organization of eukaryotic aminoacyl-tRNA-synthetases]. / Izuchenie nadmolekuliarnoi organizatsii éukarioticheskikh aminoatsil-tRNK-sintetaz.

The catalytical properties and thermostability of free leucyl-, glutamyl- and lysyl-tRNA synthetases and of the same synthetases in codosomes are compared. The stability of different aminoacyl-tRNA synthetases in highly purified preparations and in codosomes did not submit to any common regularities. Km for all substrates both for purified and assembled ARSases are values of the same order. It is shown in some model systems that the aminoacyl-tRNA synthetase activity in codosomes depends on the presence of pyrophosphatase. Other important components of codosomes are protein kinases and phospholipids which are able to influence the aminoacyl-tRNA synthetase activity and structural organization.