China University of Petroleum, Qingdao, China.
Biomacromolecules. 2010 Feb 8;11(2):402-11. doi: 10.1021/bm901130u.
Amphiphilic peptides A(3)K, A(6)K, and A(9)K displayed an increasing propensity for nanoaggregation with increasing the size of hydrophobic alanine moiety, and the size and shape of the aggregates showed a steady transition from loose peptide stacks formed by A(3)K, long nanofibers by A(6)K, to short and narrow nanorods by A(9)K. This size and shape transition was broadly consistent with the trend predicted from interfacial packing and curvature change if these peptide surfactants were treated as conventional surfactants. The antibacterial capacity, defined by the killing of percentage of bacteria in a given time and peptide concentration, showed a strong correlation to peptide hydrophobicity, evident from both microscopic and fluorescence imaging studies. For A(9)K, the power for membrane permeation and bacterial clustering intensified with peptide concentration and incubation time. These results thus depict a positive correlation between the propensity for self-assembly of the peptides, their membrane penetration power, and bactericidal capacity. Although the exposure of A(9)K to a preformed DPPC membrane bilayer showed little structural disturbance, the same treatment to the preformed DPPG membrane bilayer led to substantial disruption of model membrane structure, a trend entirely consistent with the high selectivity observed from membrane hemolytic studies.
两亲性肽 A(3)K、A(6)K 和 A(9)K 的疏水性丙氨酸部分越大，越容易发生纳米聚集，而且聚集的大小和形状也从 A(3)K 形成的松散肽堆积、A(6)K 形成的长纳米纤维，稳定地转变为 A(9)K 形成的短而窄的纳米棒。如果将这些肽表面活性剂视为常规表面活性剂，这种大小和形状的转变与界面堆积和曲率变化的趋势大致一致。用一定时间和肽浓度杀死一定数量细菌的抗菌能力与肽疏水性密切相关，这一点从显微镜和荧光成像研究中都可以明显看出。对于 A(9)K，随着肽浓度和孵育时间的增加，其膜渗透和细菌聚集的能力也随之增强。因此，这些结果表明，肽的自组装倾向、膜穿透能力和杀菌能力之间存在正相关关系。尽管 A(9)K 暴露于预先形成的 DPPC 膜双层中几乎没有结构干扰，但对预先形成的 DPPG 膜双层进行相同处理会导致模型膜结构的实质性破坏，这一趋势与从膜溶血研究中观察到的高选择性完全一致。
