title: Threonyl-tRNA synthetase from yeast: aminoacylation of tRNA on its non-accepting 3'-terminal hydroxyl group and its behaviour in enzyme-catalyzed deacylation.
abstract: Methods have been developed by which tRNA Thr may be aminoacylated at the normally non-accepting 3'-terminal ribose OH. Two of the methods utilize the mischarging ability of the synthetases under special conditions of low salt concentration and presence of organic solvents. The third method demonstrates for the first time that for some synthetases the 2',3' specificity may be manipulated by use of similar special conditions. In the case of threonyl-tRNA synthetase, Thr-tRNAThr-C-C-A(3'd) has been synthesised by this method. The behaviour of threonyl esters of tRNAThr-C-C-A, tRNAThr-C-C-A(2'd) and tRNA Thr-C-C-A-(3'd) in the free enzyme-catalyzed deacylation has been studied and the results indicate that the cis diol functional group is necessary for this hydrolysis. The position on the terminal ribose from which the amino acid is removed in this reaction remains to be identified.
mesh_terms: D000249:Adenosine Monophosphate / Q000378:metabolism; D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D011756:Diphosphates / Q000378:metabolism; D006868:Hydrolysis; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013914:Threonine-tRNA Ligase / Q000378:metabolism*; D014637:Valine-tRNA Ligase / Q000378:metabolism
chemical_list: D011756:Diphosphates; D012346:RNA, Transfer, Amino Acyl; D000249:Adenosine Monophosphate; D000604:Amino Acyl-tRNA Synthetases; D013914:Threonine-tRNA Ligase; D014637:Valine-tRNA Ligase