Studies of Copper Complexes Displaying N3S Coordination as Models for CuBCenter of Dopamine β-Hydroxylase and Peptidylglycine α-Hydroxylating Monooxygenase

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Abstract
We describe the studies of new copper complexes [MeSPY2]CuPF6, 2, and [MeSPY2]Cu(ClO4)2·CH3CN, 3, as models for the CuB center of dopamine β-hydroxylase and peptidylglycine α-hydroxylating monooxygenase. The structure of [MeSPY2]Cu(ClO4)2·CH3CN, 3, has been established by X-ray crystallography. The copper coordination exhibits a square pyramidal geometry where the equatorial plane is occupied by the SCH3 group and three nitrogen atoms (tertiary amine, one pyridine, and acetonitrile solvent), whereas the axial position binds the second pyridine. Using FEFF calculations and multiscattering interaction, EXAFS refinements show that the SMe group lies in the coordination sphere of copper complexes [MeSPY2]CuPF6, 2, and [MeSPY2]Cu(ClO4)2·CH3CN, 3. While [MeSPY2]CuPF6, 2, reacts with dioxygen in dichloromethane without oxidation of the ligand, we observed an oxidation of the sulfide ligand when [MeSPY2]Cu(ClO4)2·CH3CN, 3, reacts with hydrogen peroxide in methanol. Considering results, we propose that Met314, crucial for DBH and PHM activity, could be the site of the H2O2 (or ascorbate) inactivation by oxidation to the sulfoxide group.