| 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 |