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Spectroscopy: An International Journal
Volume 27, Article ID 674032, 7 pages

Spectroscopic Determination of pKa Constants of MADS Box Segments

1Faculty of Mathematics and Physics, Institute of Physics, Charles University in Prague, Ke Karlovu 5, 12116 Prague 2, Czech Republic
2Laboratoire Acides Nucléiques et Biophotonique, FRE 3207, Université Pierre et Marie Curie, place Jussieu 4, 75252 Paris Cedex 5, France
3Unité de Chimie des Biomolécules, URA 2128 CNRS, Institut Pasteur, rue du Dr. Roux 28, 75724 Paris Cedex 15, France

Copyright © 2012 Barbora Řezáčová et al. 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.


We have introduced a new promising approach for the determination of pKa constants of oligopeptide intrinsic fluorophores and spectral components referring to their differently charged states. The method is based on the factor analysis of multiwavelength spectroscopic pH titration data. As an illustration, we present its application on the study of short segments of the MADS box, which is a highly conserved sequence of a so-called family of transcription factors, by techniques of UV absorption and fluorescence spectroscopies. Investigated oligopeptides contain no tryptophan but one tyrosine serving as an intrinsic fluorophore and absorber. The results indicate both good sensitivity and spectroscopic selectivity of our method, which thus may be considered as a complementary technique to conventional electrochemical methods.