Spectroscopy of Mixed-Valence CuA-Type Centers: Ligand-Field Control of Ground-State Properties Related to Electron Transfer
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- 作者：Daniel R. Gamelin ; David W. Randall ; Michael T. Hay ; Robert P. Houser ; Ton C. Mulder ; Gerard W. Canters ; Simon de Vries ; William B. Tolman ; Yi Lu ; and Edward I. Solomon
- 刊名：Journal of the American Chemical Society
- 出版年：1998
- 出版时间：June 3, 1998
- 年：1998
- 卷：120
- 期：21
- 页码：5246 - 5263
- 全文大小：320K
- 年卷期：v.120,no.21(June 3, 1998)
- ISSN：1520-5126
文摘
Using a combination of electronic spectroscopies, electronicstructural descriptions have beendeveloped for a series of binuclear CuA-type centers inBacillus subtilis CcO and engineered into thebluecopper proteins Pseudomonas aeruginosa azurin andThiobacillus versutus amicyanin. Paralleldescriptionsare developed for two structurally characterized mixed-valence (MV) andhomovalent (II,II) synthetic copperthiolate dimers. Assignment of the excited-state spectral featuresallows the electronic structures of CuA andthe MV model to be understood and compared in relation to their coppercoordination environments. Theseelectronic structural descriptions are supported by SCF-X
pha.gif" BORDER=0>-SW MOcalculations, which are used to testsystematically the effects of major structural perturbations linkingthe MV model geometry to that of CuA. Itis determined that both Cu-Cu compression and removal of the axialligands are critical determinants of theorbital ground state in these dimers. The weakened axialinteractions in CuA appear to parallel themechanismfor protein control of electron transfer (ET) function observed in bluecopper centers. The major geometricand electronic features of CuA, including metal-ligandcovalency, redox potentials, reorganization energies,valence delocalization, and the weakened axial bonding interactions,are discussed in relation to its ET function,and specific potential ET pathways are identified andcompared.
pha.gif" BORDER=0>-SW MOcalculations, which are used to testsystematically the effects of major structural perturbations linkingthe MV model geometry to that of CuA. Itis determined that both Cu-Cu compression and removal of the axialligands are critical determinants of theorbital ground state in these dimers. The weakened axialinteractions in CuA appear to parallel themechanismfor protein control of electron transfer (ET) function observed in bluecopper centers. The major geometricand electronic features of CuA, including metal-ligandcovalency, redox potentials, reorganization energies,valence delocalization, and the weakened axial bonding interactions,are discussed in relation to its ET function,and specific potential ET pathways are identified andcompared.