Dr. David Merkler
B.A., University of Maryland
Ph.D., Pennsylvania State University
Post-translational, C-terminal amidation is required for the full biological activity of most mammalian peptide hormones. The critical amide moiety arises by the post-translational, oxidative cleavage of a C-terminal glycine-extended prohormone at the a-carbon of the glycine in a reaction which requires a reducing equivalent, copper, and molecular oxygen, This reaction is catalyzed in vivo by peptidylglycine a-amidating enzyme (PAM). For the past several years, the research in my laboratory has involved the basic characterization of PAM. We have demonstrated that the enzyme is a monooxygenase, determined that PAM binds 2 moles of Cu(II)/active site which redox cycle between CU(II) and Cu(I) during turnover, and established that the two enzyme-bound copper atoms are in chemically distinct environments. In addition, we have recently discovered that PAM also contains one tightly bound Zn(II)/active site and will catalyze the formation of oleamide and other fatty acid amides, a newly described class of mammalian hormones. This exciting discovery hints that PAM could play a larger role in human metabolism and opens new areas of research in my laboratory. Research will continue on PAM in order to define the mechanistic details of peptide and lipid amidation. These studies will utilize a variety of techniques, including equilibrium binding measurements, steady-state and rapid-quench kinetics, isotope effects, site-directed mutagenesis, and spectroscopic investigations of the enzyme-bound metal atoms. Long term plans for the laboratory will be to build our experience with PAM to work on other enzymes catalyzing post-translational modifications of proteins and peptides and other oxygenases. I plan to fully explore the possibility that PAM catalyzes reactions other than peptide amidation that are important to human health.