title: Ternary complex formation between elongation factor Tu, GTP and aminoacyl-tRNA: an equilibrium study.
abstract: The equilibria between the elongation factor Tu-GTP complex (EF-Tu-GTP) from Escherichia coli and tyrosyl-tRNATyr from E. coli as well as phenylalanyl-tRNAPhe and seryl-tRNASer from yeast were studied using a novel procedure, which takes advantage of the protective effect of ternary complex formation on the stability of theaminoacyl bond against non-enzymatic hydrolysis. At 25 degrees C and at pH 7.4 tyrosyl-tRNATyr, phenylalanyl-tRNAPhe and seryl-tRNASer are bound with binding constants of 0.7 X 10(7) M-1, 5.0 X 10(7) M-1 and 0.5 X 10(7) M-1 respectively. The binding of aminoacyl-tRNA to EF-Tu-GTP has a negative deltaH of the order of 10 kcal/mol (42 kJ/mol). Complex formation is dependent on ionic strength: with 0.1 M KCl Kass = 0.8 X 10(7) M-1, with 0.5 M KCl Kass = 0.2 X 10(7) M-1 was determined for the binding of Tyr-tRNATyr.
mesh_terms: D002151:Calorimetry; D004355:Drug Stability; D004926:Escherichia coli / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D046911:Macromolecular Substances; D010445:Peptide Elongation Factors; D010649:Phenylalanine; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012694:Serine; D013696:Temperature; D013816:Thermodynamics; D014443:Tyrosine
chemical_list: D046911:Macromolecular Substances; D010445:Peptide Elongation Factors; D012346:RNA, Transfer, Amino Acyl; D006153:Guanosine Diphosphate; D014443:Tyrosine; D012694:Serine; D010649:Phenylalanine; D006160:Guanosine Triphosphate