家蝇幼虫抗菌肽MDL-1的构象分析

用红外光谱、圆二色谱和荧光光谱研究家蝇幼虫抗菌肽MDL-1的结构特征及其在不同条件下的构象变化. 红外光谱检测结果显示抗菌肽MDL-1结构中含有螺旋、无规卷曲、折叠构象的吸收特征; 圆二色谱显示抗菌肽MDL-1结构相对比较稳定, 抗菌肽在不同浓度溶液中的构象发生改变; 荧光光谱法研究发现家蝇幼虫抗菌肽MDL-1在280 nm波长的激发光下, 荧光光谱为Tyr残基和Trp残基共同提供, 而且Trp残基不是位于抗菌肽分子的表面, 而是位于分子的内部, 该研究结果为进一步探讨抗菌肽的抗菌机理奠定了基础.

Conformation Analysis on Antibacterial Peptide MDL-1 from Musca domestica Larvae

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.