ABSTRACT
CufiCD/hydroperoxide, with the resultant substrate radical then promoting heterolytic cleavage of the dioxygen bond to form the peptidyl a-hydroxyglycine product (Fig. 8) [72]. Jaron and Blackburn [190] also observed differences in the properties of PHM following binding of the peptidyl glycine substrate. Before substrate binding, carbon monoxide binds only to Cub; however, binding of the peptide opens up binding of carbon monoxide at a second site, probably CuA. This impbes that substrate binding may activate the CuA center toward dioxygen binding. It was hence proposed that superoxide formed by reduction of dioxygen at CuA diffuses across the 1 1 -A channel to relocate at the CuB site, where the subsequent events in the catalytic mechanism would be similar to those proposed by Amzel (Fig. 8) [72].
