Electron density based interaction energy estimation of the special pair in the photosynthetic reaction center

• Published in: Chemical physics letters Vol. 536; pp. 129 - 135
• Main Authors: Yamasaki, Hideki, Nakamura, Haruki
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 21-05-2012
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/j.cplett.2012.03.087

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► Interactions between halves of special pair were theoretically studied. ► Two axial histidines weaken the interaction between halves of special pair. ► The acetyl and non-polar groups of special pair (SP) stabilize SP. ► Electron-density-based analyses can be an alternative to a counterpoise one.
Interactions between special pairs (SP) in the photosynthetic reaction center were studied using quantum chemical calculations in conjunction with the quantum theory of atoms in molecules. Two histidines, coordinated with Mg2+ ions of SP, weaken the interaction between SP halves. The acetyl and non-polar groups of SP stabilize SP in addition to the interaction between the macrocycles themselves.
Correlations between the interaction energies and the sum of electron densities over the bond critical points of intermolecular interactions (interρb) were found, suggesting that using electron-density-based interaction energy is a useful alternative to using the interaction energy with a counterpoise corrected method.