Isolation and Amino Acid Sequence of Physalaemin, the Main Active Polypeptide of the Skin of Physalaemus fuscumaculatus

Abstract

Crude methanol extracts of fresh and dried skins of Physalaemus fuscumaculatus, a South American amphibian, were subjected successively to chromatography on alkaline alumina and to countercurrent distribution. The main active constituent of these extracts, the polypeptide physalaemin, was thus obtained in a pure form. Total and partial acid hydrolysis, fission with trypsin and chymotrypsin, and end-group determination experiments demonstrated that physalaemin is an endecapeptide having the following amino acid composition and sequence: Pyr-Ala-Asp(OH)-Pro-Asp(NH2)-Lys-Phe-Tyr-Gly-Leu-Met-NH2 Some anomalies in the trypsin and chymotrypsin fission of physalaemin are discussed, and the strict chemical resemblance between physalaemin and eledoisin is pointed out.