Purification And Partial Characterization Of A Novel Antibacterial Peptide From Musca Domestica Larvae

Antibacterial peptides are small Mr peptides with antibacterial function produced by organisms, which are important components of innate immunity system in organisms. These peptides have characters of highly thermal stability, well water solubility, broad antibacterial spectrum and strong bactericidal activity. Some of them can kill bacteria which have resistance against traditional antibiotics, and the bactericidal mechanism impossibly makes the pathogenic bacteria occur resistance mutation. These advantages could make antibacterial peptides become perfect substitutes of antibiotics. In addition, some antibacterial peptides can inhibit or kill some virus and parasite. Furthermore, some of them can inhibit some tumour cell growing, and are harmless to human normal cell. It brings new hope for the development of anticancer drugs. Antibacterial peptide has extensive applied perspective as a natural peptide antibiotic with new bactericidal mechanism and a new anticancer drug. It has become a popular research subject in life science field to find new antibacterial peptides.Musca domestica, which belongs to insecta, diptera, cyclorrhapha, muscidae, is the most common muscae and the richest resource in our country. It is very significant and valuable to separating antibacterial peptides from Musca domestica and to develop these peptides into antibacterial medicine. Due to purify a pure peptide from natural material is very difficult, few research is in progress. Based on a highly sensitive bactericidal detection method, using dilute acetic acid extraction, alginic acid absorption, NaCl salting-out, Sephadex G25 gel filtration, CMC23 ion-exchange chromatography, RP-HPLC and electro-elution, a novel 20 kD antibacterial peptide had been purified from Musca domestica dry larvae. The peptide has antibacterial activity against Gram-positive bacteria such as Bacillus thuringiensis, Bacillus subtilis and Staphylococcus aureus. Using intracellular Ca2+ fluorimetry technique, it has been detected that the antibacterial peptide in mM make the intracellular Ca2+ concentration of pancreasβ-cell increase. And the effect is durative and not related to the dose of the antibacterial peptide.