title: Interacting binding sites of isoleucyl-tRNA synthetase from Escherichia coli studied by equilibrium partition.
abstract: The binding of tRNAIIe to isoleucyl-tRNA synthetase in the presence of isoleucine or ATP was investigated using the equilibrium partition method. Isoleucine decreased the affinity of tRNAIIe for the enzyme by a factor of about 5. For the free standard energy of interaction a value of about 1 kcal/mol (4.2 kJ/mol) was calculated. ATP exhibits qualitatively the same effect as isoleucine. A binding of two molecules isoleucine per molecule of enzyme could not be demonstrated even in the presence of ATP and pyrophosphatase.
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism; D001665:Binding Sites; D004926:Escherichia coli / Q000201:enzymology*; D007532:Isoleucine; D007533:Isoleucine-tRNA Ligase / Q000378:metabolism; D007700:Kinetics; D008433:Mathematics; D011485:Protein Binding; D012343:RNA, Transfer; D013816:Thermodynamics
chemical_list: D007532:Isoleucine; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases; D007533:Isoleucine-tRNA Ligase