Department of Physics, IBILCE, UNESP, São Paulo State University, Rua Cristovão Colombo 2265, São José do Rio Preto, SP, 15054-000, Brazil.
Eur Biophys J. 2013 Dec;42(11-12):819-31. doi: 10.1007/s00249-013-0930-0. Epub 2013 Oct 5.
Static and time-resolved fluorescence of tryptophan and ortho-aminobenzoic acid was used to investigate the interaction of the synthetic antimicrobial peptide L1A (IDGLKAIWKKVADLLKNT-NH2) with POPC and POPC:POPG. N-acetylated (Ac-L1A) and N-terminus covalently bonded ortho-aminobenzoic acid (Abz-L1A-W8V) were also used. Static fluorescence and quenching by acrylamide showed that the peptides adsorption to the lipid bilayers was accompanied by spectral blue shift and by a decrease in fluorescence quenching, indicating that the peptides moved to a less polar environment probably buried in the lipidic phase of the vesicles. These results also suggest that the loss of the N-terminus charge allowed deeper fluorophore insertion in the bilayer. Despite the local character of spectroscopic information, conclusions can be drawn about the peptides as a whole. The dynamic behaviors of the peptides are such that the mean intensity lifetimes, the long correlation time and the residual anisotropy at long times increased when the peptides adsorb in lipid vesicles, being larger in anionic vesicles. From the steady-state increase in fluorescence intensity and anisotropy, we observed that the partition coefficient of peptides L1A and its Abz analog in both types of vesicles are higher than the acetylated analog; moreover, the affinity to the anionic vesicle is higher than to the zwitterionic.
采用色氨酸和邻氨基苯甲酸的静态和时间分辨荧光法研究了合成抗菌肽 L1A（IDGLKAIWKKVADLLKNT-NH2）与 POPC 和 POPC:POPG 的相互作用。还使用了 N-乙酰化（Ac-L1A）和 N 末端共价键合邻氨基苯甲酸（Abz-L1A-W8V）。静态荧光和丙烯酰胺猝灭表明，肽与脂质双层的吸附伴随着光谱蓝移和荧光猝灭的减少，表明肽移动到了一个较少极性的环境中，可能埋藏在囊泡的脂质相中。这些结果还表明，N 末端电荷的丧失允许荧光团更深地插入双层中。尽管光谱信息具有局部特征，但可以对整个肽得出结论。肽的动态行为是，当肽在脂质囊泡中吸附时，平均强度寿命、长相关时间和长时间的剩余各向异性增加，在阴离子囊泡中更大。从荧光强度和各向异性的稳态增加，我们观察到肽 L1A 及其 Abz 类似物在两种类型的囊泡中的分配系数均高于乙酰化类似物；此外，对阴离子囊泡的亲和力高于对两性离子囊泡的亲和力。
