As an example of a very low friction system,Monte Carlo Brownian dynamics simulations have been used to calculate equilibrium structures of a polyelectrolyte brush grafted onto planes.The polymers were calculated in a...As an example of a very low friction system,Monte Carlo Brownian dynamics simulations have been used to calculate equilibrium structures of a polyelectrolyte brush grafted onto planes.The polymers were calculated in a semi-flexible coarse-grain model that is appropriate to treat the charge density of the polyion.The effect of linear charge density on the polyionx,the surface negative charge,and added salts were studied.In salt-free solution,scaling theories predicted the structure well in the lowxregion.In the highxregion,additional shrinkage was found from the theories due to counterion condensation.The effect of surface charge showed not only the repulsion of the polyion from the surface but also the shrinkage in the highxregion due to the additional counterions required for electrical neutrality.The addition of salts led to the shrinkage of the brush heights,and in the highxregion,additional extension was found.The computational strategy for calculating the friction dynamics of the system is also discussed.展开更多
The effect of channel-protein interaction on the translocation of a protein-like chain through a finite channel under certain electric field was studied by using dynamical Monte Carlo simulations. The interior behavio...The effect of channel-protein interaction on the translocation of a protein-like chain through a finite channel under certain electric field was studied by using dynamical Monte Carlo simulations. The interior behavior of chain conformation under different interactions was investigated, such as the number of monomers outside of channel nout, monomers inside of channel nm, mean-square radius of gyration 〈 S2 〉 and the average energy 〈U〉. It shows that with strong attractive interaction, the translocation is more difficult than moderate interaction. At the same time, the dependence of translocation time with different interactions shows that moderate repulsive interaction （εcp = 0.5） accelerates the translocation. Although the waiting time for successful translocation of εep = 1.0 is the longest, the average translocation time is not very large. It is far smaller than that of εep = -1.0. The probability distributions of translocation time p（t＇） and the probability distributions of three duration times p（t1＇）, p（t2＇） and p（t3＇） were all discussed. Log-normal distributions are found. All these findings will strengthen the understanding of protein translocation.展开更多
基金supported by the MEXT program“Elements Strategy Initiative to Form Core Research Center”(since 2012),MEXTMinistry of Education Culture,Sports,Science and Technology,Japan.
文摘As an example of a very low friction system,Monte Carlo Brownian dynamics simulations have been used to calculate equilibrium structures of a polyelectrolyte brush grafted onto planes.The polymers were calculated in a semi-flexible coarse-grain model that is appropriate to treat the charge density of the polyion.The effect of linear charge density on the polyionx,the surface negative charge,and added salts were studied.In salt-free solution,scaling theories predicted the structure well in the lowxregion.In the highxregion,additional shrinkage was found from the theories due to counterion condensation.The effect of surface charge showed not only the repulsion of the polyion from the surface but also the shrinkage in the highxregion due to the additional counterions required for electrical neutrality.The addition of salts led to the shrinkage of the brush heights,and in the highxregion,additional extension was found.The computational strategy for calculating the friction dynamics of the system is also discussed.
基金supported by the National Natural Science Foundation of China(No.20904047)
文摘The effect of channel-protein interaction on the translocation of a protein-like chain through a finite channel under certain electric field was studied by using dynamical Monte Carlo simulations. The interior behavior of chain conformation under different interactions was investigated, such as the number of monomers outside of channel nout, monomers inside of channel nm, mean-square radius of gyration 〈 S2 〉 and the average energy 〈U〉. It shows that with strong attractive interaction, the translocation is more difficult than moderate interaction. At the same time, the dependence of translocation time with different interactions shows that moderate repulsive interaction （εcp = 0.5） accelerates the translocation. Although the waiting time for successful translocation of εep = 1.0 is the longest, the average translocation time is not very large. It is far smaller than that of εep = -1.0. The probability distributions of translocation time p（t＇） and the probability distributions of three duration times p（t1＇）, p（t2＇） and p（t3＇） were all discussed. Log-normal distributions are found. All these findings will strengthen the understanding of protein translocation.
