Incorporation of aerobic oxygen into the hydroxyglycyl intermediate during formation of C-terminal peptide amides by peptidylglycine α-amidating monooxygenase (PAM)

Incubation of D-phenylalanyl-L-phenylalanylglycine with peptidylglycine α-amidating monooxygenase (PAM) in the presence of 18O2 generates the corresponding hydroxyglycyl peptide whose FAB mass spectrum shows high incorporation of 18O into the hydroxy group; this suggests that the mechanism may involve direct hydroxylation of carbon.