[Effect of excess D,L-tryptophan on the level of aminoacylation of tRNA by 14C-tryptophan].

The effect of the D,L-tryptophan excess in the rat organism was studied as applied to the level of amino acylation of tRNA by 14C-tryptophan. It is established that the introduction of tryptophan for three days in doses of 50 and 75 mg per 100 g of the living weight evokes a 24 and 40% decrease, respectively, in the level of amino acylation of the rat livel tRNA by 14C-tryptophan. The ability of accepting 14C-tryptophan in total preparations of the experimental rats liver tRNA considerably lower as compared to norm. A short-term heating in the presence of magnesium ions partially restores their decreased acceptor ability. This gives ground to suppose that the molecules of tRNAtr in the total preparation of the rat liver tRNA with a great tryptophan excess in the organism partially change their conformation and this is one of the reasons of the decrease in the level of tRNA amino acylation by 14C-tryptophan. The decrease in the protein synthesis at the first stage with the presence of a great tryptophan excess in the organism is evident to be also connected with the inhibition of tryptophanyl-tRNA-synthetase activity.