Abstract: The structure and conformation of antibacterial peptide MDL-1 from Musca domestica Larvae were studied by infrared spectroscopy(IR),circular dichroism(CD) and fluorescence spectrum methods. Infrared absorption spectroscopy analysis shows that it had the characteristic absorption peak of protein. Amide Ⅰ strip located at 1700—1600 cm^-1 in IR spectra. It was found that a trans-configuration in peptide bond was the major characteristic arrangement in the peptide chains, the structure of these peptides were very stable.The secondary structure of antibacterial peptides was determined in different media and under different conditions by CD measurement. A great deal of ordered α-helices and β-sheet, flexible random coil and β-turn conformation were adopted in SDS solution by imitated hydrophobic bacterial membrane means. The fluorescence spectra of MDL-1 excited to exhibit characteristic absorbency of Trp residues and Tyr residuces at 280 nm. We can deduce that the Trp residues of MDL-1 were located in the inner district with negative dielectric instead of the surface. This research provides a foundation for the analysis of antibacterial function.

Key words: Musca domestica larvae, Antibacterial peptide, Conformation