Unblocked statistical-coil tetrapeptides in aqueous solution: quantum-chemical computation of the carbon-13 NMR chemical shifts

Journal of Biomolecular NMR
Jorge A VilaHarold A Scheraga

Abstract

We recently reported a theoretical characterization of representative ensembles of statistical-coil conformations for tetrapeptides with unblocked termini in aqueous solution, at pH 7. The results showed good agreement between the computed Boltzmann-averaged and experimentally-determined values for both the vicinal coupling constants (3)J(NHalpha) and the alpha-proton chemical shifts. Here, we carry out a cluster analysis of the ensembles of conformations generated in that study, and use them to compute the Boltzmann-averaged values of the quantum-chemical (13)C chemical shifts for different amino acids in the unblocked tetrapeptides GGXA (where X stands for Phe, Arg, His, Glu, Ile, Lys, Gln, Tyr, Leu, Thr, Ala, Gly and Val). The values of the (13)C chemical shifts in these thirteen amino acids (for which experimental data are available) were computed by using Density Functional Theory with a 6-311+G(2d,p) basis set. Good agreement is found in terms of both the correlation coefficient (R) and standard deviations of the difference between the computed Bolztmann-averaged and the NMR-determined values for the (13)C chemical shifts. These results suggest that it may be possible to build a reliable theoretically-derived database of ...Continue Reading

Citations

Sep 9, 2005·Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences·Eric Oldfield
Jun 15, 2007·Journal of Biomolecular NMR·Jorge A VilaHarold A Scheraga
Oct 23, 2004·Protein Science : a Publication of the Protein Society·Jorge A VilaHarold A Scheraga
Dec 21, 2006·Journal of Biomolecular NMR·Myriam E VillegasHarold A Scheraga
Jul 29, 2004·Organic & Biomolecular Chemistry·Gianluigi LuppiClaudia Tomasini
Apr 15, 2010·Journal of the American Chemical Society·Itzam De GortariMichele Vendruscolo

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