title: Threonyl-tRNA, lysyl-tRNA and arginyl-tRNA synthetases from Baker's yeast. Substrate specificity with regard to ATP analogues.
abstract: Sixteen analogues of ATP have been tested in the aminoacylation reaction of threonyl-tRNA, lysyl-tRNA, and arginyl-tRNA synthetases from baker's yeast. Two compounds are substrates for threonyl-tRNA and for lysyl-tRNA synthetases and five compounds for arginyl-tRNA synthetase. There are six inhibitors for threonyl-tRNA, nine for lysyl-tRNA, and six for arginyl-tRNA synthetase. Their Km and Ki values have been determined. Thus positions 2, 6, 7, 8 and 9 of the purine moiety and 2' and 3' of the sugar moiety of the ATP molecule are important for catalytic action of these aminoacyl-tRNA synthetases. Remarkably arginyl-tRNA synthetase is the first aminoacyl-tRNA synthetase which tolerates bulky substituents at the sugar moiety of ATP. These data fit with the idea that synthetases of subunit structure need magnesium-ion-ATP complexes with an anti conformation as substrates whereas single-chain enzymes accept this substrate in the syn conformation.
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives*; D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D001126:Arginine-tRNA Ligase / Q000378:metabolism; D007700:Kinetics; D008250:Lysine-tRNA Ligase / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013914:Threonine-tRNA Ligase / Q000378:metabolism
chemical_list: D000255:Adenosine Triphosphate; D000604:Amino Acyl-tRNA Synthetases; D001126:Arginine-tRNA Ligase; D013914:Threonine-tRNA Ligase; D008250:Lysine-tRNA Ligase