Solvation effects on S K-edge XAS spectra of Fe-S proteins: normal and inverse effects on WT and mutant rubredoxin.

ABSTRACT: S K-edge X-ray absorption spectroscopy (XAS) was performed on wild type Cp rubredoxin and its Cys --> Ser mutants in both solution and lyophilized forms. For wild type rubredoxin and for the mutants where an interior cysteine residue (C6 or C39) is substituted by serine, a normal solvent effect is observed, that is, the S covalency increases upon lyophilization. For the mutants where a solvent accessible surface cysteine residue is substituted by serine, the S covalency decreases upon lyophilization which is an inverse solvent effect. Density functional theory (DFT) calculations reproduce these experimental results and show that the normal solvent effect reflects the covalency decrease due to solvent H-bonding to the surface thiolates and that the inverse solvent effect results from the co

SUBMITTER: Sun N 

PROVIDER: S-EPMC2946794 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature