Isolation and Molecular Cloning of Insulinotropic Peptide from the Skin Secretions of Amolops loloensis and the Study of Its Bioactivities

To investigate the bioactive component from the skin secretion of Amolops loloensis , isolated peaks with insulin-releasing activity were purified and structurally determined. Skin secretions were isolated by Gel filtration and Reversed phase high-performance liquid chromatography, and tested with insulin-releasing assay. The amino acid sequence of bioactive peak was determined by Edman degradation and identified by gene clone method. A 16-amino peptide with obvious insulin-releasing activity was obtained and sequenced as FMPIVGKSMSGLSGKL-NH₂ , which was designated amolopin-1. The precursor peptide composed of 64 amino acid residues deduced from cloned skin cDNA (open reading frame 192 bp) exhibited a highly-conserved signal peptide (22aa), an acidic amino acid residue-rich domain and an amolopin-1 encoding domain. Structural alignment with database records revealed that a novel insulinotropic peptide was obtained from skin secretion of Amolops loloensis therefore further study of its acting mechanism and pharmacokinetics may lead to the discovery of a new treatment for diabetes.