xmacs / shenzl.github.io Goto Github PK
View Code? Open in Web Editor NEWsci-blog
License: GNU General Public License v2.0
sci-blog
License: GNU General Public License v2.0
Combining classical molecular dynamics simulations and density functional theory calculations, we find that cations block water flow through narrow (6,6)-type carbon nanotubes (CNTs) because of interactions between cations and aromatic rings in CNTs. In wide CNTs, these interactions trap the cations in the interior of the CNT, inducing unexpected open or closed state switching of ion transfer under a strong electric field, which is consistent with experiments. These findings will help to develop new methods to facilitate water and ion transport across CNTs.
set zmax 8.6
set lambda 1.6
set Pi 3.14159265
proc calcforces {step unique eps} {
global zmax lambda Pi
while {[nextatom]} {
if { [getmass] < 22.9 || [getmass] > 23.0} {
dropatom
continue
}
set z [lindex [getcoord] 2]
set f [expr 1.1*$eps*$lambda/$Pi* \ (1/(($lambda*($z+$zmax))**2+1) - 1/(($lambda*($z-$zmax))**2+1))]
addforce [list 0 0 $f]
addenergy [expr 1.1*$eps/$Pi* \ (atan($lambda*($z-$zmax)) + atan($lambda*(-$z-$zmax)))]
}
}
模版网站:RCSB
根据需要获得蛋白质的pdb文件,获得pdb文件后,仔细阅读前面remark内容(内容居然基本是大写字母,有时真是不忍卒读啊!想开发个对pdb文件中内容总结的编辑器或者编辑器插件,虽然目前有pdb浏览软件,但都感觉有各项不足。。。。想到pdb文件中的结构有更好地了解,建议阅读与pdb文件相关的出版文献),了解蛋白是否存在残基或原子缺失的情况。
如果pdb文件中不存在残基缺失的情况,这个步骤可以直接略过。
此步骤可以由许多同源建模软件(MOE, DS等)完成,这里介绍下Chimera与Modeller联用补全缺失残基的方法。(本例以蛋白4RM8为例)
在VMD-Tkconcle中运行下列tcl脚本即可。拓扑文件与力场参数文件由VMD提供。
mol load pdb 4rm8_new.pdb
set protein_A [atomselect top "protein and chain A"]
$protein_A writepdb a.pdb
set protein_B [atomselect top "protein and chain B"]
$protein_B writepdb b.pdb
resetpsf
package require psfgen
topology ./top_all36_prot.rtf
topology ./top_all27_prot_lipid.rtf
topology ./top_all36_cgenff.rtf
pdbalias atom ILE CD1 CD
pdbalias atom HOH O OH2
pdbalias residue HOH TIP3
pdbalias residue HIC HSE
segment A {
first NTER
last CTER
pdb a.pdb
}
segment B {
first NTER
last CTER
pdb b.pdb
}
coordpdb a.pdb A
coordpdb b.pdb b
guesscoord
writepdb protein.pdb
writepsf protein.psf
file delete a.pdb b.pdb
mol delete all
package require topotools
package require pbctools
mol new protein.psf
mol addfile protein.pdb
topo writegmxtop protein.top [list ./par/par_all36_prot.prm ./par/par_all27_prot_lipid.prm ./par/par_all36_cgenff.prm] ###生成gromacs的top文件,可在后期数据处理时使用,在模拟中有时会出错,不建议在模拟中使用
得到protein.pdb与protein.psf文件便是我们需要的蛋白质模型文件。
A declarative, efficient, and flexible JavaScript library for building user interfaces.
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
An Open Source Machine Learning Framework for Everyone
The Web framework for perfectionists with deadlines.
A PHP framework for web artisans
Bring data to life with SVG, Canvas and HTML. 📊📈🎉
JavaScript (JS) is a lightweight interpreted programming language with first-class functions.
Some thing interesting about web. New door for the world.
A server is a program made to process requests and deliver data to clients.
Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.
Some thing interesting about visualization, use data art
Some thing interesting about game, make everyone happy.
We are working to build community through open source technology. NB: members must have two-factor auth.
Open source projects and samples from Microsoft.
Google ❤️ Open Source for everyone.
Alibaba Open Source for everyone
Data-Driven Documents codes.
China tencent open source team.