[Mechanism of functioning of aminoacyl-tRNA-synthetases]

The article reviews the data available concerning the kinetics of reactions catalysed by eukaryotic and procaryotic aminoacyl-tRNA synthetases (E.C.6.1.1). It is shown that most of these enzymes operate in accordance with the flip-flop mechanism although individual variations do exist. It is stressed that a simplified kinetic approach of Cleland is inappropriate if applied to the aminoacyl-tRNA synthetases where subunit interactions are involved in the overall kinetics. The fidelity of aminoacylation reaction depends not only on the proofreading mechanisms at catalytic centres but also on the contribution of mutual conformational changes induced in interacting subunits of the synthetases.