Purification and Characterization of a Peptide C-Terminal α-Amidating Enzyme from Porcine Atrium

Abstract

In many peptide hormones and neuropeptides, the carboxy-terminal α-amide structure is essential in eliciting biological activity. Here we report the purification and characteriza-tion of an α-amidating enzyme from porcine atrium, in which a high concentration of α-amidating activity was detected. The enzyme was purified to homogeneity from the membrane fraction of porcine atria by five steps of chromatography, including an affinity chromatography using a Sepharose column coupled with a substrate, Tyr-Phe-Gly. The purified enzyme was found to be composed of a single polypeptide chain with an apparent molecular weight of 92, 000. This enzyme converted several synthetic peptides with C-terminal glycine to the corresponding des-glycine peptide α-amides.