荧光光谱分析家蝇幼虫抗菌肽与大肠杆菌染色体DNA作用机理

Study on the Interaction Mechanism of Antibacterial Peptide MDL-1 in Musca Domestica L and E. coli DNA by Fluorescence Spectra

利用荧光光谱方法研究了家蝇幼虫抗菌肽MDL- 1与大肠杆菌染色体DNA的相互作用 ,并以溴化乙锭为荧光探针 ,考察了抗菌肽MDL- 1结合大肠杆菌DNA的作用方式 ,探讨其作用模式 ,即 :抗菌肽MDL- 1与大肠杆菌DNA骨架的磷酸基团通过静电引力结合 ,使抗菌肽MDL- 1和DNA的空间结构都发生变化 ,抗菌肽MDL- 1进一步与DNA双螺旋的沟槽结合 ,然后抗菌肽MDL- 1以嵌入或部分嵌入方式与DNA相互作用 ,计算出抗菌肽MDL- 1与DNA的结合常数和成键位点数。本试验从分子水平上研究抗菌肽与细菌DNA的作用模式和结构特征 ,对深入了解抗菌肽的作用机理极为重要。

In this paper, the interaction of the antibacterial peptide MDL-1 of Musca domestica L and E. coli DNA was investigated by fluorescence spectra. The interaction mode was studied by using ethidium bromide (EB) as an extrinsic fluorescence probe. The result of fluorescence spectra and Scatchard plot indicate that the binding constant and the number of binding sites between DNA and EB decrease with increasing concentration of MDL-1. The change in binding constant and binding sites showed that the conformation of DNA transformed. When the EB molecule just fitted into the interval, the fluorescence intensity was maximum. When MDL-1 was present in the system, the EB molecules was excluded from DNA, then the fluorescence intensity decreased. The result showed that the style was eletrostatic binding, groove binding and intercalation in the interaction of MDL-1 and double helix DNA. The binding constant of MDL-1 complex with DNA was determined. Meanwhile, it helped to explain the molecule mechanism of antibacterial peptides from the interaction style and structure characteristic of antibacterial peptide and bacterial DNA.