ABSTRACT
The acceptor capacity of tRNAs and tRNA-synthetases activities of liver extracts was compared for rabbits of different age groups. The level of maximum tRNA aminoacylation in vitro of newborn rabbit (3-5 days) liver for glycine, glutamic acid, leucine, tryptophan, and phenylalanine and tRNA of old rabbits (5 years) liver for glutamic acid, leucine, phenylalanine, and glycine was 1,5-3 times lesser in comparison to that of 1 and 2 years rabbits. The pool of endogenous aminoacyl-tRNAs in 3-5 days rabbits liver was also considerably lower for above mentioned amino acids. The results of short-term heating of tRNA preparations in the presence of Mg2- given the possibility to assume that the decreases tRNA preparations in the presence of Mg2+ give the possibility to assume that the decreases tRNA acceptor activity of the newborn animals depends upon the presence of tRNA inactive conformers. Another reason is the greater loss of the CCA-end in mentioned tRNA. None of these factors in the reason of low acceptor activity of old rabbit liver tRNA which seems to be caused by more considerable disturbances in he molecular structure. Aminoacyl-tRNA-synthetases activities of liver extracts of the same age groups increases during development of animals and decrease subsequently in the liver of old (5 years) rabbits. However, dynamics and quantitative characteristics of these changes are not similar for enzymes of different amino acid specificities.
