Planarians are one of the simplest animal groups with a central nervous system. Their primitive central nervous system produces large quantities of a variety of neuropeptides, of which many are amidated at their C terminus. In vertebrates, peptide amidation is catalyzed by two enzymes [peptidylglycine a-hydroxylating monooxygenase (PHM) and peptidyl-a-hydroxylglycinea-amidating lyase] acting sequentially. In mammals, both enzymatic activities are contained within a single protein that is encoded by a single gene
