Journal of the American Chemical Society · 2002 · 43 citations · 16 references
Natural SciencesBiochemistryChemistryComputational ChemistryQuantum ChemistryTheoretical ChemistryAb Initio MethodsConfiguration InteractionElectronic StructureHyperfine StructureMolecular Orbital TheoryMultireference MethodsAb Initio CalculationsEffective Core PotentialsElectronic Structure AnalysisMolecular Orbital AnalysisMolecular Orbital DelocalizationParamagnetic CentersParamagnetism In Coordination CompoundsSpin Densities In Molecules
The electronic structure of the blue-copper site of Pseudomonas aeruginosa azurin has been investigated by ab initio multireference determinantal configuration interaction (MRD-CI) calculations. A truncated site consisting of copper and its three equatorial ligands has been studied with emphasis on the g tensor and the nitrogen hyperfine tensors of the coordinating histidines. In the ground state the singly occupied molecular orbital (SOMO) involves a copper 3d orbital pi antibonded to the cysteine sulfur and sigma antibonded to the histidine nitrogens. A proper description of the electron-paramagnetic-resonance parameters has been achieved through the use of an effective core potential for copper up to and including the 3s electrons. Both the complete g tensor and the anisotropic hyperfine tensors at the nitrogens are essentially reproduced. Mulliken spin densities of 35 and 59% on copper and sulfur, respectively, and 2.1 and 1.7% on the respective coordinating nitrogens reflect the delocalized character of the SOMO and the inequivalence of the histidines.
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Susan E. Shadle, James E. Penner‐Hahn, Harvey J. Schugar et al. · Journal of the American Chemical Society · 1993 · 298 citations