拉曼光谱研究乳铁蛋白及其肽段与DPPC、DPPG脂质体的相互作用

摘要

利用拉曼光谱研究了乳铁蛋白及其肽段Lactofcrrcin B4-14和Lactoferrampin与DPPC、DPPG脂质体的相互作用.通过分析作用前后两种磷脂拉曼光谱的变化,探讨了乳铁蛋白及其肽段与磷脂的作用模式,为阐明乳铁蛋白及其肽段抗菌机理提供了重要依据.拉曼光谱显示,乳铁蛋白及其肽段加入中性磷脂DPPC脂质体后,属于磷脂脂酰链的C-H对称、反对称伸缩振动的2 847和2 882 cm-1处的峰强没有发生明显改变;而当乳铁蛋白及其肽段与DPPG作用后,2 882 cm1处的峰强度明显下降,磷脂的侧向相互作用序参数由未加入时的0.19分别下降到了0.17,0.14,0.12,变化率分别为-11%,-27%,-34%,表明乳铁蛋白及其肽段可能通过静电相瓦作用与负电性DPPG脂质体吸引并结合,且Lactoferrcin B4-14和Lactoferrampin比乳铁蛋白与磷脂的作用更为强烈.%Interaction of lactoferrin and its peptides LfcinB4-14 and LfampinB with dipalmitoylglycero-phosphocholine (DPPC) and dipalmitoylglycero-phosphoglycerol (DPPG) liposomes were studied by means of Raman spectroscopy. In our study,conformational changes in the phospholipid molecules were investigated by measuring the intensities of 2 847 and 2 882 cm-1 Raman bands which are assigned to acyl chains' symmetric and asymmetric C—H stretching vibrations. The addition of lactoferrin and its peptides LfcinB4-14 and LfampinB caused a decrease in the 2 882 cm-1 intensity of DPPG liposomes, thus the order parameter for the lateral interactions between chains Slat decreased from 0. 19 to 0.17, 0. 14 and 0. 12 respectively. On the contrary, the intensities at 2 847 and 2 882 cm-1 of DPPC liposomes were poorly affected by lactoferrin and its peptides. The results show that lactoferrin and its peptides present a stronger effect on the molecular structure and order degree of anionic lipid DPPG than that of zwitterionic lipid DPPC. This suggests that lactoferrin, LfcinB4-14 and LfampinB can interact and combine with the negatively charged DPPG liposomes by electrostatic interaction and perform its antibacterial activity. Besides,LfcinB4-14 and LfampinB can affect the lipid more strongly than lactoferrin.