Table of Contents
ISRN Biophysics
Volume 2012 (2012), Article ID 124803, 5 pages
http://dx.doi.org/10.5402/2012/124803
Research Article

Density Functional Theory Study on Metal-Binding Energies for Human Serum Transferrin-Metal Complexes

1Faculty of Nutritional Sciences, The University of Morioka, Takizawa, Iwate 020-0183, Japan
2Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1–3 Kagurazaka, Shinjyuku-ku, Tokyo 162-8601, Japan

Received 16 December 2011; Accepted 3 January 2012

Academic Editors: D. Bulone and P. G. Fajer

Copyright © 2012 Tetsuya Sakajiri 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.

Abstract

The absolute values of the metal-binding energies of human serum transferrin (Tf) N-lobe, | Δ E | , were calculated using the density functional theory and were found to increase in magnitude in the following order: Fe(III)>Ga(III)>Al(III)>Cu(II)>Zn(II)>Ni(II). The calculated energies were well correlated with the logarithmic values of the reported metal-binding constants of Tf, which had been experimentally determined, with a correlation coefficient of 0.96. In the estimation of the binding energies, the solvation energies (solvent effect) of free metal ions were a very important factor. The results provide a theoretical explanation for the binding of Fe(III) to Tf, which produces sufficient energy to induce a conformational transition of the Tf molecule, making it possible to interact with Tf receptor 1.