Force‐field dependence of Boltzmann weighting factors on predicted π‐π*circular dichroic spectra of cyclo(Gly‐Pro‐Gly)2
- 1 June 1996
- journal article
- Published by Wiley in International Journal of Peptide and Protein Research
- Vol. 47 (6) , 447-459
- https://doi.org/10.1111/j.1399-3011.1996.tb01095.x
Abstract
Semi-empirical energy calculations were performed for published conformations of cyclo (Gly-Pro-Gly)2 using different force fields (DISCOVER cvff and cff91, AMBER, and CHARMM). The resulting potential energies were then used to create Boltzmann weighting factors for an ensemble of cyclo(Gly-Pro-Gly)2 structures. The dipole interaction model was used to predict pi-pi* circular dichroic spectra (CD) for the individual structures of cyclo(Gly-Pro-Gly)2. The Boltzmann weighting factors were applied to the individual spectra so that a composite spectrum was constructed to represent a CD arising from a collection of different structures in solution. Weighting factors determined from different force fields were compared. Boltzmann-weighted spectra better resembled the experimental CD than any calculated spectrum using only a single conformation of cyclo (Gly-Pro-Gly)2. The structures most heavily weighted contained at least one type I beta-turn.Keywords
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