X-RAY STUDY OF Cu(II)GHK COPPER-CONTAINING PEPTIDE COMPLEXES
M.A. Kremennaya, M.A. Soldatov, Y.S. Podkovyrina, I.A. Dadasheva, A.V. Soldatov
International Scientific Center "Smart Materials", Rostov-on-Don, Russia
Keywords: комплекс Cu(II)GHK, XANES, локальная атомная структура, пептид, метод конечных разностей, Cu(II)GHK complex, local atomic structure, peptide, finite difference technique
Abstract
The Cu(II)GHK (Cu(II)-Gly-His-Lys (glycyl-hystidyl-lysine) complex is of interest as a model peptide for the elaboration of a procedure to study the structure of metal centers in proteins, in particular, the copper binding center in β-amyloid. X-ray absorption spectra are measured for an aqueous solution of Cu(II)GHK. The stability of the complex under X-ray radiation is controlled by optical spectroscopy. Structural models with different coordinations of the copper center, which were constructed based on the crystallographic structure, are considered. Based on the analysis of theoretical X-ray absorption spectra of the derived structures, two optimal models are chosen. For the selected models the structural parameters are optimized. It is found that the best agreement with the experiment is observed for the spectrum of a five-coordinated model with water molecules in the equatorial and lower axial positions with Cu-O distances of 1.97 Å and 2.31 Å respectively.
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