Purification and Characterization of a Peptide C-Terminal α-Amidating Enzyme from Porcine Atrium1

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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 characterization 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.