[Interaction between tryptophanyl-tRNA synthetase and tryptophan analogs with modified alpha-amino group].

Analogs of L-tryptophane with modified alpha-amino groups (substituted for hydrogen or keto-group, or acylated) are competitive reversible inhibitors of the aminoacylation of tRNNATrp catalyzed by tryptophanyl-tRNA synthetase from beef pancreas. Compounds lacking alpha-amino group are weakly bound to the enzyme, whereas the Ki values for N-acylated L-tryptophane derivates and for beta-indolylpyruvic acid are similar and approximately two orders of magnitude higher than the KM value for L-tryptophane.