| Autor: |
Johansson, Magnus, Ka-Weng leong, Trobro, Stefan, Strazewski, Peter, Åqvist, Johan, Pavlov, Michael Y., Ehrenberg, Måns |
| Předmět: |
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| Zdroj: |
Proceedings of the National Academy of Sciences of the United States of America; 1/4/2011, Vol. 108 Issue 1, p79-84, 6p, 3 Diagrams, 1 Chart, 2 Graphs |
| Abstrakt: |
We studied the pH-dependence of ribosome catalyzed peptidyl transfer from fMet-tRNAfMet to the aa-tRNAs Phe-tRNAPhe, Ala- tRNAAla, Gly-tRNAGly, Pro-tRNAPro, Asn-tRNAAsn, and lle-tRNAlle, selected to cover a large range of intrinsic pKa-values for the α-amino group of their amino acids. The peptidyl transfer rates were different at pH 7.5 and displayed different pH-dependence, quantified as the pH-value, pKobsa at which the rate was half maximal. The pKaobsa-values were downshifted relative to the intrinsic pKa-value of aa-tRNAs in bulk solution. Gly-tRNAGly had the smallest downshift. while lle-tRNAlle and Ala-tRNAAlahad the largest downshifts. These downshifts correlate strongly with molecular dynamics (MD) estimates of the downshifts in pKa-values of these aa-tRNAs upon A-site binding. Our data show the chemistry of peptide bond formation to be rate limiting for peptidyl transfer at pH 7.5 in the Gly and Pro cases and indicate rate limiting chemistry for all six aa-tRNAs. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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