文献类型：期刊文献

英文题名：Binding structure and kinetics of surfactin monolayer formed at the air/water interface to counterions: A molecular dynamics simulation study

作者：Gang, Hongze[1,2];Liu, Jinfeng[1,2];Mu, Bozhong[1,2,3]

机构：[1]E China Univ Sci & Technol, State Key Lab Bioreactor Engn, Shanghai 200237, Peoples R China;[2]E China Univ Sci & Technol, Inst Appl Chem, Shanghai 200237, Peoples R China;[3]Shanghai Collaborat Innovat Ctr Biomfg Technol, Shanghai 200237, Peoples R China

年份：2015

卷号：1848

期号：10

起止页码：1955

外文期刊名：BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000362153400001)】；

基金：This work was financially supported by the National Science Foundation of China (21203063), the 863 Program (2013AA064403) and the Fundamental Research Funds for the Central Universities of China (nos. WK1213003, WJ1214066).

语种：英文

外文关键词：Surfactin monolayer; Counterion; Binding affinity; Salt bridge; Break rate

摘要：The binding structure and kinetics of ionized surfactin monolayer formed at the air/water interface to five counterions, Li+, Na+, K+, Ca2+, and Ba2+ (molar ratios of surfactin to monovalent and divalent counterions are 1:2 and 1:1 respectively), have been studied using molecular dynamics simulation. The results show that surfactin exhibits higher binding affinity to divalent counterions, Ca2+, and Ba2+, and smaller monovalent counterion, Li+, than Na+ and K+. Both carboxyl groups in surfactin are accessible for counterions, but the carboxyl group in Glul is easier to access by counterions than Asp5. Salt bridges are widely built between carboxyl groups by counterions, and the probability of the formation of intermolecular salt bridge is markedly larger than that of intramolecular salt bridge. Divalent counterions perform well in forming salt bridges between carboxyl groups. The salt bridges mediated by Ca2+ are so rigid that the lifetimes are about 0.13 ns, and the break rates of these salt bridges are 1-2 orders of magnitude smaller than those mediated by K+ which is about 5 ps in duration. The positions of the hydration layer of carboxyl groups are independent of counterions, but the bound counterions induce the dehydration of carboxyl groups and disturb the hydrogen bonds built between carboxyl group and hydration water. (C) 2015 Elsevier B.V. All rights reserved.