Preparation and Characterization of Half-Apo Dopamine-.beta.-hydroxylase by Selective Removal of CuA. Identification of a Sulfur Ligand at the Dioxygen Binding Site by EXAFS and FTIR Spectroscopy

Progress has been made in determining the individual coordination of each of the copper sites (Cu A and Cu B ) which comprise the active center in dopamine-β-hydroxylase. Previous studies have determined the average ligand environment per copper in the fully metalated enzyme as two to three histidines and one to two O/N donors in the Cu(II) form changing to 2-3 histidines and 0.5 sulfur donors upon reduction to the Cu(I) form. Derivatives of the Cu(I) form of DBH have been made in which CuA has been selectively removed, allowing Cu B , the O 2 -binding center to be studied by EXAFS and FTIR