Biopolymers and cell. 2009; 25 (4): 298 - 306

 

 

Study on models of O2 binding to heme using density functional theory

 

B. F. Minaev, V. A. Minaeva, E. N. Obushko, D. Ì. Hovorun1

 

B. Khmelnyckyy Cherkasy National University 81, Shevchenko str., Cherkassy, Ukraine, 18031
1Institute of molecular biology and genetics NAS of Ukraine 150, Zabolotnogo Str, Kyiv Ukraine, 03680

 

Aim. To study a mechanism of molecular oxygen binding to heme three models of geometry structure of the complex are considered: the axis of O2 molecule is situated perpendicularly to the porphin macrocycle, parallel, and angularly. Methods. The Fe(II) porphin complexes with dioxygen are calculated by the quantum-chemical method of density functional theory with the UB3LYP/6-311G approximation. Results. The optimized geometry and electron structures as well as the absorption IR spectra of the complexes in the high-spin (septet) state are described. Conclusions. It is shown that the main mechanism of spin-orbit coupling during the O2 binding to heme is connected with peculiarity of the O2 molecule electronic structure.

 

Keywords: oxyhemoglobin, spin states, IR absorption spectrum, spin-orbit coupling.