Copper K-extended x-ray absorption fine structure studies of oxidized and reduced dopamine beta-hydroxylase. Confirmation of a sulfur ligand to copper(I) in the reduced enzyme.

The structure of the copper sites in oxidized and reduced dopamine beta-hydroxylase has been studied by extended x-ray absorption fine structure spectroscopy using a restrained refinement approach to data analysis. An histidine-rich active site has been found to be present with an average histidine coordination of between two and three histidine ligands per copper. In the oxidized protein, the data support four-coordination, involving two to three imidazole groups at 1.

Carbonmonoxy dopamine beta-hydroxylase. Structural characterization by Fourier transform infrared, fluorescence, and x-ray absorption spectroscopy.

The carbon monoxide complex of ascorbate-reduced dopamine beta-hydroxylase has been prepared and characterized by Fourier transform infrared, fluorescence, and x-ray absorption spectroscopies. CO has previously been shown to be a competitive inhibitor with respect to O2, and binds to only one of the two copper atoms/active site (Blackburn, N. J.

Characterization of a carbon monoxide complex of reduced dopamine beta-hydroxylase. Evidence for inequivalence of the Cu(I) centers.

Ascorbate-reduced dopamine beta-hydroxylase (DBH) is inhibited by CO in a competitive manner with respect to molecular O2. Measurement of the stoichiometry of CO binding indicates 0.50 CO bound per Cu(I), which provides the first evidence that the Cu(I) centers in the reduced enzyme are structurally inequivalent.