Number of GTPs hydrolysed on EF-TU per petide bond

Value 2.2 ~P
Organism Bacteria Escherichia coli
Reference Bilgin N, Claesens F, Pahverk H, Ehrenberg M. Kinetic properties of Escherichia coli ribosomes with altered forms of S12. J Mol Biol. 1992 Apr 20 224(4):1011-27.PubMed ID1569565
Method A quench-flow device with a time resolution of about one millisecond is used to start elongation by rapidly mixing initiated ribosomes with ternary complex and to quench the reaction at different time points after mixing. With this technique researchers have characterized different steps during the translation cycle of wild-type ribosomes, such as GTP hydrolysis on EF-Tu and dipeptide formation. Researchers have used the same technique to study the time evolution of the first few elongation cycles of poly(Phe) synthesis. They have, in particular, investigated how mutations in the ribosomal protein S12 or the presence of Sm influence different steps in the ribosomal elongation cycle.
Comments When a cognate ternary complex associates with the programmed A-site, GTP is rapidly hydrolysed on EF-Tu. Subsequently, the binary EF-Tu. GDP complex leaves the ribosome and peptidyl transfer occurs (Kaziro, 1978). From the extent of GTP hydrolysis at long times (GDP(8)) and the extent of peptide bond formation at long times (dip(8)) researchers calculate that the number of GTPs per peptide bond (fC = GDP(8)/dip(8)) is about 2.2.
Entered by Uri M
ID 105066