title: Mechanisms of suppression in Drosophila. IV. Specificity and properties of tyrosyl-tRNA synthetase.
abstract: Tyrosyl-tRNA synthetase from wide type Drosophila can distinguish tRNATyr of wild type from that of the suppressor mutant, su(s)2. The method of fractionation of the enzyme on DEAE-cellulose can produce three different forms of the enzyme. One of these forms is characterized in this study. We describe the apparent Km for K+, Mg2+, ATP, tyrosine and tRNA, as well as its heat stability and molecular weight. Spermine does not replace Mg2+ but is inhibitory, a Ki of 1 mM was obtained. Inhibition by p-chloromercuribenzoate results in a Ki of 1 muM. The properties of tyrosyl-tRNA synthetase of Drosophila are compared to the properties of this enzyme from E. coli, B. subtilis and yeast.
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D000818:Animals; D004331:Drosophila melanogaster / Q000201:enzymology*; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D013045:Species Specificity; D013096:Spermine / Q000494:pharmacology; D013489:Suppression, Genetic; D014448:Tyrosine-tRNA Ligase / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D013096:Spermine; D000604:Amino Acyl-tRNA Synthetases; D014448:Tyrosine-tRNA Ligase; D008274:Magnesium; D011188:Potassium