2018 AMBER tutorial with 1c87
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Revision as of 13:24, 26 March 2018 by AMS536 2018 02 (talk | contribs)
In this tutorial, we will learn how to run a MD simulation of a protein-ligand complex and learn how to calculate structural fluctuations (with RMSD) and free energies of binding (MM-GBSA).
I. Prepare the files and directories
We can create the directories to make all the files organized.
~username/AMS536/2018/Amber_Tutorial/000.parameters
/001.tleap_build
/002.equilibration
/003.production
/004.analysis
/zzz.master
Once the directories are created, we are going to convert 1c87_lig_withH_charged.mol2 file and 1c87_rec_withH_charged.mol2 file to pdb file in chimera, then copy the converted files into zzz.master directory.
II. Structural Preparation
Before we submit our jobs for equilibration or production, we must parametrize the ligands by using antechamber and check for any missing force field parameters. Make sure we have the proper partial charge. Since there are two acids in the 1c87 structure, -nc will be -2.
cd 000.parameters # Parameterize the ligand antechamber -i ../zzz.master/2nnq.lig.withH.charged.for_antechamber.pdb -fi pdb -o 2nnq_lig.am1bcc.mol2 -fo mol2 -at gaff2 -c bcc -rn LIG -nc -2 # Check for missing FF parameters parmchk2 -i 2nnq_lig.am1bcc.mol2 -f mol2 -o 2nnq_lig.am1bcc.frcmod
Then, we will create the topology and coordinate files for the simulation through tleap. Create a file called tleap.in with the following:
#!/usr/bin/sh
###Load Protein force field
source leaprc.protein.ff14SB
###Load GAFF force field (for our ligand)
source leaprc.gaff
###Load TIP3P (water) force field
source leaprc.water.tip3p
####Load Ions frcmod for the tip3p model
loadamberparams frcmod.ionsjc_tip3p
###Needed so we can use igb=8 model
set default PBradii mbondi3
###Load Protein pdb file
rec=loadpdb ../zzz.master/rec_withH_1c87.pdb
###Load Ligand frcmod/mol2
loadamberparams ../000.parameters/1c87_lig.am1bcc.frcmod
lig=loadmol2 ../000.parameters/1c87_lig.am1bcc.mol2
###Create gas-phase complex
gascomplex= combine {rec lig}
###Write gas-phase pdb
savepdb gascomplex 1c87.gas.complex.pdb
###Write gas-phase toplogy and coord files for MMGBSA calc
saveamberparm gascomplex 1c87.gas.complex.prmtop 1c87.gas.complex.rst7
saveamberparm rec 1c87.gas.receptor.prmtop 1c87.gas.receptor.rst7
saveamberparm lig 1c87.gas.ligand.prmtop 1c87.gas.ligand.rst7
###Create solvated complex (albeit redundant)
solvcomplex= combine {rec lig}
###Solvate the systemsolvateoct
solvcomplex TIP3PBOX 12.0
###Neutralize system (it will add either Na or Cl depending on net charge)
addions solvcomplex Cl- 0
addions solvcomplex Na+ 0
###Write solvated pdb file
savepdb solvcomplex 1c87.wet.complex.pdb
###Check the system
charge solvcomplex
check solvcomplex
###Write Solvated topology and coord file
saveamberparm solvcomplex 1c87.wet.complex.prmtop 1c87.wet.complex.rst7
Create Amber topology and coordinates files for the MD simulation.
tleap -f tleap.in
III. Equilibration
We can now create the input files for the equilibration of the system in 002.equilbration directory. We are going to run minimization in order to remove steric clashes and allow the receptor and ligand to equilibrate into a low energy state (MD simulation).
01.min.mdin:
Minmize all the hydrogens &cntrl imin=1, ! Minimize the initial structure maxcyc=5000, ! Maximum number of cycles for minimization ntb=1, ! Constant volume ntp=0, ! No pressure scaling ntf=1, ! Complete force evaluation ntwx= 1000, ! Write to trajectory file every ntwx steps ntpr= 1000, ! Print to mdout every ntpr steps ntwr= 1000, ! Write a restart file every ntwr steps cut= 8.0, ! Nonbonded cutoff in Angstroms ntr=1, ! Turn on restraints restraintmask=":1-298 & !@H=", ! atoms to be restrained restraint_wt=5.0, ! force constant for restraint ntxo=1, ! Write coordinate file in ASCII format ioutfm=0, ! Write trajectory file in ASCII format /
02.equil.mdin:
MD simualation &cntrl imin=0, ! Perform MD nstlim=50000 ! Number of MD steps ntb=2, ! Constant Pressure ntc=1, ! No SHAKE on bonds between hydrogens dt=0.001, ! Timestep (ps) ntp=1, ! Isotropic pressure scaling barostat=1 ! Berendsen taup=0.5 ! Pressure relaxtion time (ps) ntf=1, ! Complete force evaluation ntt=3, ! Langevin thermostat gamma_ln=2.0 ! Collision Frequency for thermostat ig=-1, ! Random seed for thermostat temp0=298.15 ! Simulation temperature (K) ntwx= 1000, ! Write to trajectory file every ntwx steps ntpr= 1000, ! Print to mdout every ntpr steps ntwr= 1000, ! Write a restart file every ntwr steps cut= 8.0, ! Nonbonded cutoff in Angstroms ntr=1, ! Turn on restraints restraintmask=":1-298 & !@H=", ! atoms to be restrained restraint_wt=5.0, ! force constant for restraint ntxo=1, ! Write coordinate file in ASCII format ioutfm=0, ! Write trajectory file in ASCII format iwrap=1, ! iwrap is turned on /
03.min.mdin:
Minmize all the hydrogens &cntrl imin=1, ! Minimize the initial structure maxcyc=1000, ! Maximum number of cycles for minimization ntb=1, ! Constant volume ntp=0, ! No pressure scaling ntf=1, ! Complete force evaluation ntwx= 1000, ! Write to trajectory file every ntwx steps ntpr= 1000, ! Print to mdout every ntpr steps ntwr= 1000, ! Write a restart file every ntwr steps cut= 8.0, ! Nonbonded cutoff in Angstroms ntr=1, ! Turn on restraints restraintmask=":1-298 & !@H=", ! atoms to be restrained restraint_wt=2.0, ! force constant for restraint ntxo=1, ! Write coordinate file in ASCII format ioutfm=0, ! Write trajectory file in ASCII format /
04.min.mdin:
Minmize all the hydrogens &cntrl imin=1, ! Minimize the initial structure maxcyc=1000, ! Maximum number of cycles for minimization ntb=1, ! Constant volume ntp=0, ! No pressure scaling ntf=1, ! Complete force evaluation ntwx= 1000, ! Write to trajectory file every ntwx steps ntpr= 1000, ! Print to mdout every ntpr steps ntwr= 1000, ! Write a restart file every ntwr steps cut= 8.0, ! Nonbonded cutoff in Angstroms ntr=1, ! Turn on restraints restraintmask=":1-298 & !@H=", ! atoms to be restrained restraint_wt=0.1, ! force constant for restraint ntxo=1, ! Write coordinate file in ASCII format ioutfm=0, ! Write trajectory file in ASCII format /
05.min.mdin:
Minmize all the hydrogens &cntrl imin=1, ! Minimize the initial structure maxcyc=1000, ! Maximum number of cycles for minimization ntb=1, ! Constant volume ntp=0, ! No pressure scaling ntf=1, ! Complete force evaluation ntwx= 1000, ! Write to trajectory file every ntwx steps ntpr= 1000, ! Print to mdout every ntpr steps ntwr= 1000, ! Write a restart file every ntwr steps cut= 8.0, ! Nonbonded cutoff in Angstroms ntr=1, ! Turn on restraints restraintmask=":1-298 & !@H=", ! atoms to be restrained restraint_wt=0.05, ! force constant for restraint ntxo=1, ! Write coordinate file in ASCII format ioutfm=0, ! Write trajectory file in ASCII format /
06.equil.mdin:
MD simualation &cntrl imin=0, ! Perform MD nstlim=50000 ! Number of MD steps ntb=2, ! Constant Pressure ntc=1, ! No SHAKE on bonds between hydrogens dt=0.001, ! Timestep (ps) ntp=1, ! Isotropic pressure scaling barostat=1 ! Berendsen taup=0.5 ! Pressure relaxtion time (ps) ntf=1, ! Complete force evaluation ntt=3, ! Langevin thermostat gamma_ln=2.0 ! Collision Frequency for thermostat ig=-1, ! Random seed for thermostat temp0=298.15 ! Simulation temperature (K) ntwx= 1000, ! Write to trajectory file every ntwx steps ntpr= 1000, ! Print to mdout every ntpr steps ntwr= 1000, ! Write a restart file every ntwr steps cut= 8.0, ! Nonbonded cutoff in Angstroms ntr=1, ! Turn on restraints restraintmask=":1-298 & !@H=", ! atoms to be restrained restraint_wt=1.0, ! force constant for restraint ntxo=1, ! Write coordinate file in ASCII format ioutfm=0, ! Write trajectory file in ASCII format iwrap=1, ! iwrap is turned on /
07.equil.mdin:
MD simulation &cntrl imin=0, ! Perform MD nstlim=50000 ! Number of MD steps ntx=5, ! Positions and velocities read formatted irest=1, ! Restart calculation ntc=1, ! No SHAKE on for bonds with hydrogen dt=0.001, ! Timestep (ps) ntb=2, ! Constant Pressure ntp=1, ! Isotropic pressure scaling barostat=1 ! Berendsen taup=0.5 ! Pressure relaxtion time (ps) ntf=1, ! Complete force evaluation ntt=3, ! Langevin thermostat gamma_ln=2.0 ! Collision Frequency for thermostat ig=-1, ! Random seed for thermostat temp0=298.15 ! Simulation temperature (K) ntwx= 1000, ! Write to trajectory file every ntwx steps ntpr= 1000, ! Print to mdout every ntpr steps ntwr= 1000, ! Write a restart file every ntwr steps cut= 8.0, ! Nonbonded cutoff in Angstroms ntr=1, ! Turn on restraints restraintmask=":1-298 & !@H=", ! atoms to be restrained restraint_wt=0.5, ! force constant for restraint ntxo=1, ! Write coordinate file in ASCII format ioutfm=0, ! Write trajectory file in ASCII format iwrap=1, ! iwrap is turned on /
08.equil.mdin:
MD simulations &cntrl imin=0, ! Perform MD nstlim=50000 ! Number of MD steps ntx=5, ! Positions and velocities read formatted irest=1, ! Restart calculation ntc=1, ! No SHAKE on for bonds with hydrogen dt=0.001, ! Timestep (ps) ntb=2, ! Constant Pressure ntp=1, ! Isotropic pressure scaling barostat=1 ! Berendsen taup=0.5 ! Pressure relaxtion time (ps) ntf=1, ! Complete force evaluation ntt=3, ! Langevin thermostat gamma_ln=2.0 ! Collision Frequency for thermostat ig=-1, ! Random seed for thermostat temp0=298.15 ! Simulation temperature (K) ntwx= 1000, ! Write to trajectory file every ntwx steps ntpr= 1000, ! Print to mdout every ntpr steps ntwr= 1000, ! Write a restart file every ntwr steps cut= 8.0, ! Nonbonded cutoff in Angstroms ntr=1, ! Turn on restraints restraintmask=":1-298 & !@H=", ! atoms to be restrained restraint_wt=0.1, ! force constant for restraint ntxo=1, ! Write coordinate file in ASCII format ioutfm=0, ! Write trajectory file in ASCII format iwrap=1, ! iwrap is turned on /
09.equil.mdin:
MD simulations &cntrl imin=0, ! Perform MD nstlim=50000 ! Number of MD steps ntx=5, ! Positions and velocities read formatted irest=1, ! Restart calculation ntc=1, ! No SHAKE on for bonds with hydrogen dt=0.001, ! Timestep (ps) ntb=2, ! Constant Pressure ntp=1, ! Isotropic pressure scaling barostat=1 ! Berendsen taup=0.5 ! Pressure relaxtion time (ps) ntf=1, ! Complete force evaluation ntt=3, ! Langevin thermostat gamma_ln=2.0 ! Collision Frequency for thermostat ig=-1, ! Random seed for thermostat temp0=298.15 ! Simulation temperature (K) ntwx= 1000, ! Write to trajectory file every ntwx steps ntpr= 1000, ! Print to mdout every ntpr steps ntwr= 1000, ! Write a restart file every ntwr steps cut= 8.0, ! Nonbonded cutoff in Angstroms ntr=1, ! Turn on restraints restraintmask=":1-298 & !@H=", ! atoms to be restrained restraint_wt=0.1, ! force constant for restraint ntxo=1, ! Write coordinate file in ASCII format ioutfm=0, ! Write trajectory file in ASCII format iwrap=1, ! iwrap is turned on /
Create a submission script md.equilibration.sh in order to start equilibration.
vi md.equilibration.sh
#!/bin/sh
#PBS -N 1c87_equilibration
#PBS -l walltime=12:00:00
#PBS -l nodes=2:ppn=28
#PBS -j oe
#PBS -q long
cd $PBS_O_WORKDIR
echo "Started Equilibration on `date` "
do_parallel="sander"
prmtop="../001.tleap_build/1c87.wet.complex.prmtop"
coords="../001.tleap_build/1c87.wet.complex"
MDINPUTS=(01.min 02.equil 03.min 04.min 05.min 06.equil 07.equil 08.equil 09.equil)
for input in ${MDINPUTS[@]}; do
$do_parallel -O -i ${input}.mdin -o ${input}.mdout -p $prmtop -c ${coords}.rst7 -ref ${coords}.rst7 -x ${input}.trj -inf ${input}.info -r ${input}.rst7
coords=$input
done
echo "Finished Equilibration on `date` "
Submit the job
qsub md.equilibration.sh
Once submitted the job, info, rst7, trj files will be created for each input file.
