Objective:To identify a novel bombesin bioactive peptide from the skin secretion of Hylarana Latouchii, and to explore its effect on insulin secretion in islet cells.Methods:The skin secretion from Hylarana Latouchii was extracted by electrical stimulation, and the single chain of bombesin peptide was cloned and sequenced. The peptide QUB2995 was synthesized via solid-phase synthesis, then purified using reversed-phase high performance liquid chromatography (HPLC). Matrix assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF) was applied to validate. QPCR and ELISA were used to probe the effect of QUB2995 on insulin secretion in MIN6 and INS-1 cells.Results:A novel bombesin peptide named QUB2995 (GAFGDFLKGAAKA GALKILSIAQCKLSGTC) was found in the skin secretion of Hylarana Latouchii through molecular cloning. The bioactive peptide could significantly promote the proliferation and insulin secretion from mouse islet MIN6 cells and rat islet INS-1 cells. The effect reached a climax at the concentration of 10 -5 mol/L. Conclusion:A novel bombesin bioactive peptide named QUB2995 was found from Hylarana Latouchii. It could significantly promote insulin secretion in MIN6 cells of mouse islets and INS-1 cells of rat islets, indicating its potential in the treatment of diabetes.

BACKGROUND:Frog active peptides have rich activities,such as antibacterial and anti-tumor,and are expected to solve the problem of antibiotic resistance. OBJECTIVE:The active peptide QUB2984 was discovered in the skin secretions of Agalychnis callidryas.Its structure and properties were simulated by bioinformatics.The peptide was synthesized,purified,and identified and its biological functions were investigated. METHODS:Agalychnis callidryas skin secretions were collected by electrostimulation.The sequence of QUB2984 was obtained through constructing a cDNA library with isolated mRNA.BLAST was used for peptide sequence alignment.Besides that,Iterative Threading ASSEmbly Refinement(I-TASSER)and HeliQuest tools were used for protein secondary structure simulation.It was synthesized by solid-phase peptide synthesis,purified by reverse-phase high-performance liquid chromatography,and structurally confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.The purified peptide was used to evaluate its biological activity.Its antibacterial effect was evaluated by the minimum inhibitory concentration method.Its cytotoxic effect was detected by MTT assay.Its safety was investigated by a hemolysis test. RESULTS AND CONCLUSION:(1)Peptide QUB2984 had basically α-spiral structure,with a relatively intact hydrophobic surface,and a certain destructive ability to biofilm.The third amino acid position of QUB2984 was composed of W and had a G-X-G structure.(2)The minimum inhibitory concentration of QUB2984 against gram-positive Staphylococcus aureus was 2 μmol/L,the minimum inhibitory concentration against gram-negative Escherichia coli was 2 μmol/L,and the minimum inhibitory concentration against the fungus Candida albicans was 8 μmol/L.(3)The active peptide QUB2984 had obvious inhibitory effect on human non-small cell lung cancer cells NCI-H838 at 10-5 mol/L concentration,and the hemolytic effect on horse red cells at 64 μmol/L concentration was 50%.(4)The results showed that QUB2984 had anti-bacterial and anti-cancer activity,and it had a positive charge of +3,which was conducive to contact with bacteria or cells.