Kd of Complex I (peptidyl-tRNA in the A-site) and EF-G-GTP

Value 0.27 µM
Organism Bacteria Escherichia coli
Reference Yu H, Chan YL, Wool IG. The identification of the determinants of the cyclic, sequential binding of elongation factors tu and g to the ribosome. J Mol Biol. 2009 Feb 27386(3):802-13.PubMed ID19154738
Method Preparation of ribosomes, [14C]Phe-tRNA, and N-Ac-[14C]Phe-tRNA, Formation of ribosome tRNA complexes, Chemical footprinting, Treatment of ribosome complexes with sarcin or PAP, Binding of EF-G to ribosome complexes
Comments the apparent Kd for Complex I is 0.27 µM, whereas the Kd for Complex II is 3.04 µM, suggesting that Complex I has at least an 11-fold-higher affinity for EF-G than Complex II if indeed Complex II binds EF-G at all Note-the Kd for the binding of EF-G•GTP to vacant ribosomes, determined in a separate experiment, is 0.27 µM—the same as for binding to Complex I.
Entered by Uri M
ID 103824