抗菌肽BF2-A/B对细菌表面特性的影响及与脂质体的相互作用

Antimicrobial peptides, BF2-A/B, on the influence to bacterial surface characteristics and interaction with liposomes

摘要:

研究抗菌肽BuforinⅡ的衍生肽BF2-A/B对细菌表面特性的影响, 以及与脂质体的作用模式。Zeta电位仪和十六烷萃取法检测发现BF2-A/B作用G?菌和G+菌后, 能够提高细胞表面电负性和疏水性。选用卵磷脂和心磷脂制备包裹钙黄绿素的脂质体, 模拟细菌胞膜, 考察发现BF2-A/B能够引起荧光素从脂质体中泄漏, BF2-B对膜的扰动作用更大, 引起的泄漏率比BF2-A高, 但它们都不破裂脂质体膜。用FITC标记衍生肽, 研究发现加入脂质体后, FITC-肽荧光光谱蓝移, 量子产率增大, 并且脂质体保护FITC-肽免受丙烯酰胺的荧光淬灭, 说明BF2-A/B的N-端插入了脂质体的磷脂双分子层中。

Abstract:

In this paper, the influence to bacterial surface characteristics and interaction mode with liposomes of antimicrobial peptides BF2-A and BF2-B, two analogues of Buforin Ⅱ, had been researched. The both peptides could enhance the electronegativity and hydrophobicity of cell surface of Gram-positive bacteria and Gram-negative bacteria, which determined by Zeta potential electrometer and hexadecane extraction, respectively. BF2-A/B could cause calcein release from large unilamellar liposomes consisted of the anionic lipid phosphatidylglycerol and the zwitteronic lipid phosphatidylcholine, which reflected the compositions of bacterial cytoplasmic membrane. BF2-A displayed much weaker leakage than that of BF2-B, suggesting that BF2-B might cause perturbation of the phospholipid bilayer of the plasma membrane. However, BF2-A/B didn’t collapse the membrane of liposomes. Then the peptides were labeled with FITC. The blue shift of fluorescence spectra and the augmentation of quantum yield of FITC-peptides were discovered after the addition of liposomes. And the fluorescence quenching of FITC-peptides by acrylamide was prevented under the protection of liposomes, which implied that the N-terminal of BF2-A/B inserted into the phospholipid bilayer of membrane.