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Charge-transfer transitions in the vacuum-ultraviolet of protein circular dichroism spectra

Bulheller, B.M. and Miles, Andrew J. and Wallace, Bonnie A. and Hirst, J.D. (2008) Charge-transfer transitions in the vacuum-ultraviolet of protein circular dichroism spectra. Journal of Physical Chemistry B 112 (6), pp. 1866-1874. ISSN 1520-6106.

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Official URL: http://dx.doi.org/10.1021/jp077462k

Abstract

Circular dichroism (CD) is widely used in the structural characterization and secondary structure determination of proteins. The vacuum UV region (below 190 nm), where charge-transfer transitions have an influence on the CD spectra, can be accessed using synchrotron radiation circular dichroism (SRCD) spectroscopy. Recently, charge-transfer transitions in a conformationally diverse set of dipeptides have been characterized ab initio using complete active space self-consistent field calculations, and the relevant charge distributions have been parametrized for use in the matrix method for calculations of protein CD. Here, we present calculations of the vacuum UV CD spectra of 71 proteins, for which experimental SRCD spectra and X-ray crystal structures are available. The theoretical spectra are calculated considering charge-transfer and side chain transitions. This significantly improves the agreement with experiment, raising the Spearman correlation coefficient between the calculated and the experimental intensity at 175 nm from 0.12 to 0.79. The influence of the conformation on charge-transfer transitions is analyzed in detail, showing that the n → π* charge-transfer transitions are most important in α-helical proteins, whereas in β strand proteins the π → π* charge-transfer transition along the chain in the amino- to carboxy-end direction is most dominant.

Item Type: Article
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Biological Sciences
Depositing User: Administrator
Date Deposited: 04 Aug 2010 14:09
Last Modified: 17 Apr 2013 12:17
URI: http://eprints.bbk.ac.uk/id/eprint/1185

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