Metal Ion Dependent Adhesion Sites in Integrins: A Combined DFT and QMC Study on Mn2+

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• 作者：Eider San Sebastian ; Jon M. Matxain ; Leif A. Eriksson ; Roland H. Stote ; Annick Dejaegere ; Fernando P. Cossio ; Xabier Lopez
• 刊名：Journal of Physical Chemistry B
• 出版年：2007
• 出版时间：August 2, 2007
• 年：2007
• 卷：111
• 期：30
• 页码：9099 - 9103
• 全文大小：73K
• 年卷期：v.111,no.30(August 2, 2007)
• ISSN：1520-5207

文摘

The theoretical study of relative energies of different spin states of Mn²⁺ has been carried out for the isolatedcation and for structures in which the cation is coordinated to ligands that represent the first coordinationshell in a protein environment that contains a metal ion dependent adhesion site (MIDAS, found in the ligandbinding domain of protein LFA-1). The calculations determine whether the ligand field generated by a prototypeprotein environment affects the relative energies between high, intermediate, and low spin states. Geometryoptimizations and vibrational frequency calculations were carried out at the B3LYP/SKBJ+* level of theory.Single point calculations were performed at the B3LYP/6-311++G(2df,2p) and diffusion monte carlo (DMC)levels for the refinement of the electronic energies. These calculations reveal important differences in therelative energies between high/low spin complexes obtained by B3LYP and DMC and show that althoughboth DFT and DMC show similar trends, a higher level method such as DMC is necessary for a quantitativedescription of the interactions between Mn²⁺ and its natural ligands. (G)s of acetate-type ligand bindingreactions were calculated that show that the higher the spin of the manganese complex, the lower the affinityfor the ligand.