Valyl‐tRNA, Isoleucyl‐tRNA and Tyrosyl‐tRNA Synthetase from Baker's Yeast

Abstract

Nineteen analogs of ATP were tested in the aminoacylation reaction of valyl-tRNA [EC 6.1.1.9] isoleucyl-tRNA [EC 6.1.1.5] and tyrosyl-tRNA [EC 6.1.1.1] synthetases from Baker''s yeast. Four compounds are substrates for valyl-tRNA and 2 for isoleucyl-tRNA synthetase, but there is no modified substrate for the tyrosyl-tRNA synthetase. There is 1 inhibitor for valyl-tRNA synthetase, 8 compounds inhibit isoleucyl-tRNA synthetase and 2 compounds inhibit tyrosyl-tRNA synthetase. Their Km , Ki and V [velocity] values were determined. The substrate specificity shows that positions 2,6,7,8,9,2'', and 3'' of ATP are important for catalytic action of these aminoacyl-tRNA synthetases.