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Interaction between Antimicrobial Peptide CM15 and a Model Cell Membrane Affected by CM15 Terminal Amidation and the Membrane Phase State

Year: 2021

Journal: Langmuir, Volume 37, FEB 2, page 1613–1621

Authors: Ma, Liang; Luo, Yongsheng; Ma, Yong-Hao; Lu, Xiaolin

Organizations: State Key Development Programs for Basic Research of China [2017YFA0700500, 2016YFA0501604]; National Natural Science Foundation of China [21574020]; Fundamental Research Funds for the Central Universities; Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD); National Demonstration Center for Experimental Biomedical Engineering Education (Southeast University)

Antimicrobial peptides (AMPs) have been proposed as an effective class of antimicrobial agents against microorganisms. In this work, the interaction between an antimicrobial peptide, CM15, and a negatively charged phospholipid bilayer, DPPG, was studied via sum frequency generation (SFG) vibrational spectroscopy. Two structurally correlated characteristic variables were introduced to reveal the interaction mechanism/efficiency, i.e. C-terminal amidation and temperature variation (similar to 20 degrees C, room temperature, and similar to 35 degrees C, close to human body temperature). Experimental results indicated that owing to the increased positive charge, C-terminal amidation resulted in rapid adsorption onto the bilayer surface and efficient disruption of the outer layer, exhibiting less ordered insertion orientation. The elevated temperature (from similar to 20 degrees C to similar to 35 degrees C) promoted the penetration of both the outer and inner leaflets by the peptides and finally led to the disruption of the whole bilayer owing to the enhanced fluidity of the bilayer. From the perspective of the interaction mechanism, this experimental study provides two practical cues to understand the disruption process of the negatively charged model biomembranes, which can lay the structural foundation for designing and developing high-efficiency antimicrobial peptides.