[Study of the supramolecular organization of eukaryotic aminoacyl-tRNA-synthetases]

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.