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Spectroscopy
Volume 24 (2010), Issue 3-4, Pages 213-217
http://dx.doi.org/10.3233/SPE-2010-0429

Raman optical activity study of poly-L-proline chains of various lengths

V. Profant,1,3 M. Šafarík,2 P. Bour,2 and V. Baumruk1

1Faculty of Mathematics and Physics, Institute of Physics, Charles University in Prague, Prague, Czech Republic
2Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
3 Faculty of Mathematics and Physics, Institute of Physics, Charles University in Prague, Ke Karlovu 5, Prague 2 CZ-121 16, Czech Republic

Copyright © 2010 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Raman and Raman optical activity (ROA) spectra of several oligo- and poly-L-proline samples of various chain lengths were measured in a wide frequency range between 120 and 1800 cm−1 and analysed with respect to the main peptide chain conformation. Specifically, formation of polyproline II (PPII) helical conformation was studied in dependence on the increasing chain length N of the (L-proline)N sample. Due to high sensitivity of the ROA technique to the conformational stability and rigidity of peptide chain we were able to determine the characteristic spectral peaks associated with formation of stable PPII helical conformation in studied systems. The most relevant peaks are located at 405, 535 and 945 cm−1. Additionally, based on our data analysis, we were able to determine the minimal length of (L-proline)N chain necessary for creation of the stable PPII conformation as N = 6.