Mechanistic studies on prolyl-4-hydroxylase: Demonstration that the ferrylintermediate does not exchange with water

Prolyl-4-hydroxylase catalyzes the formation of 4-hydroxyproline in collage ns. In contrast to deacetoxy/deacetylcephalosporin C synthase, p-hydroxyphe nylpyruvate hydroxylase, lysyl hydroxylase and alpha -ketoisocaproate oxyge nase, no incorporation of O-18-Labeled water into the hydroxylated product was found for the human type I prolyl-4-hydroxylase when N-Cbz-Gly-L-Phe-L- Pro-Gly-OEt was used as a substrate. This suggests that the ferryl intermed iate for this enzyme is not solvent accessible. (C) 2000 Academic Press.