Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (11): 3035-3040.doi: 10.3866/PKU.WHXB20101116

• PHOTOCHEMISTRY AND SPECTROSCOPY • Previous Articles     Next Articles

Effect ofWater Ligation on the Redox Potential and Infrared Spectra of Chlorophyll-a

HU Qiong, WANG Guo-Ying, OU Jia-Ming, WANG Rui-Li   

  1. College of Physics and Electronic Information, Yunnan Normal University, Kunming 650092, P. R. China
  • Received:2010-05-18 Revised:2010-08-04 Published:2010-10-29
  • Contact: WANG Rui-Li E-mail:ruiliw@yahoo.com
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (10764006).

Abstract:

In the reaction center of photosystem I the accessory electron transfer cofactors are two monomeric chlorophyll-a molecules that are ligated to two water molecules. To study the effect of water ligation on the redox potential and vibrational properties of chlorophyll-a, we built three molecular models of water ligation of chlorophyll-a based on the X-ray crystal structure of photosystem I. Then, we systematically calculated the geometries, vibrational frequencies, bond dissociation energies, and redox potentials of these models using density functional theory. The calculations were conducted in the gas phase, water, and a simulated protein environment. In addition, three different basis sets were employed to investigate the influence of the basis set on the calculation results. 15N, 2H, and 13C labeled spectra of the models in the gas phase were also calculated. Our results show that the water ligand causes the Mg ion of chlorophyll-a to move away fromthe center of the porphyrin ring so that the Mg—N bond lengths increase and the Mg centered angles decrease. When a nearby amino acid, asparagine (ASNB591), provides a hydrogen bond to the water that is axial ligand to the chlorophyll-a, these changes increase further. Additionally, the Mg—O bond distance decreases, the dissociation energy increases, and the redox potential also decreases. Furthermore, the redox potentials of the molecules and their bond dissociation energies decrease as the relative die../../journalx_wlhx_en/authorLogOn.action">Online Submission
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  • Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (11): 3035-3040.doi: 10.3866/PKU.WHXB20101116

    • PHOTOCHEMISTRY AND SPECTROSCOPY • Previous Articles     Next Articles

    Effect ofWater Ligation on the Redox Potential and Infrared Spectra of Chlorophyll-a

    HU Qiong, WANG Guo-Ying, OU Jia-Ming, WANG Rui-Li   

    1. College of Physics and Electronic Information, Yunnan Normal University, Kunming 650092, P. R. China
    • Received:2010-05-18 Revised:2010-08-04 Published:2010-10-29
    • Contact: WANG Rui-Li E-mail:ruiliw@yahoo.com
    • Supported by:

      The project was supported by the National Natural Science Foundation of China (10764006).