Effect of pH and ligand binding on the structure of the Cu site of the Met121Glu mutant of azurin from Pseudomonas aeruginosa

The detailed structure of the copper center of Pseudomonas aeruginosa Met121Glu azurin mutant was analyzed by hydrogen-ion concentration (pH)-dependent X-ray absorption fine structure (XAFS) analysis. XAFS analysis of the Cu(II) center of Met121Glu indicated the presence of pH-dependent changes on the conformation of the copper site. The copper center forms four strong bonds at pH eight with longer Cu-His bond distances.