Surface tension effects on the phase transition of a DPPC bilayer with and without protein: a molecular dynamics simulation

2014 ◽  
Vol 16 (18) ◽  
pp. 8434-8440 ◽  
Author(s):  
Xian Kong ◽  
Shanshan Qin ◽  
Diannan Lu ◽  
Zheng Liu

A coarse-grained molecular dynamics simulation was applied to illustrate the phase transition behavior of the pure DPPC bilayer and aquaporin-embedded DPPC bilayer under different surface tensions.

Author(s):  
Negin Maftouni ◽  
Mehriar Amininasab ◽  
MohammadReza Ejtehadi ◽  
Farshad Kowsari

One of the most important biological components is lipid nanobio membrane. The lipid membranes of alive cells and their mechanical properties play an important role in biophysical investigations. Some proteins affect the shape and properties of the nanobio membrane while interacting with it. In this study a multiscale approach is experienced: first a 100ns all atom (fine-grained) molecular dynamics simulation is done to investigate the binding of CTX A3, a protein from snake venom, to a phosphatidylcholine lipid bilayer, second, a 5 micro seconds coarse-grained molecular dynamics simulation is carried out to compute the pressure tensor, lateral pressure, surface tension, and first moment of lateral pressure. Our simulations reveal that the insertion of CTX A3 into one monolayer results in an asymmetrical change in the lateral pressure and distribution of surface tension of the individual bilayer leaflets. The relative variation in the surface tension of the two monolayers as a result of a change in the contribution of the various intermolecular forces may be expressed morphologically and lead to deformation of the lipid membrane.


2011 ◽  
Vol 39 (1) ◽  
pp. 44-58 ◽  
Author(s):  
Y. Masumoto ◽  
Y. Iida

Abstract The purpose of this work is to develop a new analytical method for simulating the microscopic mechanical property of the cross-linked polymer system using the coarse-grained molecular dynamics simulation. This new analytical method will be utilized for the molecular designing of the tire rubber compound to improve the tire performances such as rolling resistance and wet traction. First, we evaluate the microscopic dynamic viscoelastic properties of the cross-linked polymer using coarse-grained molecular dynamics simulation. This simulation has been conducted by the coarse-grained molecular dynamics program in the OCTA) (http://octa.jp/). To simplify the problem, we employ the bead-spring model, in which a sequence of beads connected by springs denotes a polymer chain. The linear polymer chains that are cross-linked by the cross-linking agents express the three-dimensional cross-linked polymer network. In order to obtain the microscopic dynamic viscoelastic properties, oscillatory deformation is applied to the simulation cell. By applying the time-temperature reduction law to this simulation result, we can evaluate the dynamic viscoelastic properties in the wide deformational frequency range including the rubbery state. Then, the stress is separated into the nonbonding stress and the bonding stress. We confirm that the contribution of the nonbonding stress is larger at lower temperatures. On the other hand, the contribution of the bonding stress is larger at higher temperatures. Finally, analyzing a change of microscopic structure in dynamic oscillatory deformation, we determine that the temperature/frequency dependence of bond stress response to a dynamic oscillatory deformation depends on the temperature dependence of the average bond length in the equilibrium structure and the temperature/frequency dependence of bond orientation. We show that our simulation is a useful tool for studying the microscopic properties of a cross-linked polymer.


2019 ◽  
Vol 52 (10) ◽  
pp. 3787-3793 ◽  
Author(s):  
Yusuke Yasuda ◽  
Masatoshi Toda ◽  
Koichi Mayumi ◽  
Hideaki Yokoyama ◽  
Hiroshi Morita ◽  
...  

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