class DelphiBindingEnergy( object ):
"""
Determine the electrostatic component of the free energy of binding using
several rounds of Delphi calculations. DelphiBindingEnergy accepts a
binary complex (L{Biskit.Dock.Complex}) as input, performs several house
keeping tasks (optional capping of free terminals, h-bond optimization and
protonation with the reduce program, assignment of Amber partial atomic
charges) and then calls Delphi six times:
1 - 3: one run each for complex, receptor, and ligand with zero ionic
strength
4 - 6: one run each for complex, receptor, and ligand with custom salt
concentration (default: physiological 0.15 M).
The grid position and dimensions are determined once for the complex and
then kept constant between all runs so that receptor, ligand and complex
calculations can indeed be compared to each other.
The free energy of binding is calculated as described in the Delphi
documentation -- see: delphi2004/examples/binding.html -- according to the
energy partioning scheme:
dG = dG(coulomb) + ddG(solvation) + ddG(ions)
Please have a look at the source code of DelphiBindingEnergy.bindingEnergy()
for a detailed breakup of these terms.
Use:
====
>>> com = Biskit.Complex( 'myrec.pdb', 'mylig.pdb' )
>>> dg = DelphiBindingEnergy( com, verbose=True )
>>> r = dg.run()
Variable r will then receive a dictionary with the free energy of binding
and its three components:
{'dG_kt': free E. in units of kT,
'dG_kcal': free E. in units of kcal / mol,
'dG_kJ': free E. in units of kJ / mol,
'coul': coulomb contribution in kT ,
'solv': solvation contribution in kT,
'ions': salt or ionic contribution in kT }
The modified complex used for the calculation (with hydrogens added and
many other small changes) can be recovered from the DelphiBindingEnergy
instance:
>>> modified_com = dg.delphicom
The run() method assigns the result dictionary to the info record
of both the original and the modified complex. That means:
>>> r1 = com.info['dG_delphi']
>>> r2 = modified_com.info['dG_delphi']
>>> r1 == r2
True
The result of the original DelPhi calculations (with and without salt for
receptor, ligand and complex) are assigned to the info dictionaries of the
complex' receptor and ligand model as well as to the complex itself:
com.info['delphi_0.15salt'] ...delphi run with 0.15M salt on complex
com.info['delphi_0salt'] ...delphi run without salt on complex
com.lig().info['delphi_0.15salt'] ...delphi run with 0.15M salt on ligand
com.lig().info['delphi_0salt'] ...delphi run without salt on ligand
com.rec().info['delphi_0.15salt'] ...delphi run with 0.15M salt on receptor
com.rec().info['delphi_0salt'] ...delphi run without salt on receptor
From there the individual values for solvation, ionic and couloumb
contributions can be recovered. See L{Biskit.Delphi} for a description of
this result dictionary.
Customization:
==============
The most important Delphi parameters (dielectric, salt concentration,
grid scales, ion and probe radius) can be adjusted by passing parameters
to the constructor (see documentation of __init__). The default parameters
should be reasonable. By default,
we create a grid that covers every linear dimension to at least 60%
(perfil=60) and has a density of 2.3 points per Angstroem (scale=2.3).
Such high densities come at much larger computational cost. It is
recommended to test different values and average results.
Note: Any parameters that are not recognized by
DelphiBindingEnergy() will be passed on to the Biskit.Delphi instance
of each Delphi run and, from there, passed on to Biskit.Executor.
The internal pipeline of DelphiBindingEnergy consists of:
* adding hydrogens and capping of protein chain breaks and terminals with
Biskit.Reduce( autocap=True ). The capping is performed by
L{Biskit.PDBCleaner} called from within Reduce.
* mapping Amber partial atomic charges into the structure with
Biskit.AtomCharger()
* setting up the various delphi runs with L{Biskit.Delphi}.
A point worth looking at is the automatic capping of protein chain
breaks and premature terminals with ACE and NME residues. This should
generally be a good idea but the automatic discovery of premature C-termini
or N-termini is guess work at best. See L{Biskit.PDBCleaner} for a more
detailed discussion. You can override the default behaviour by setting
autocap=False (no capping at all, this is now the default) and you can
then provide a complex structure that is already pre-treated by
L{Biskit.Reduce}.
For example:
>>> m = PDBModel('mycomplex.pdb')
>>> m = Reduce( m, capN=[0], capC=[2] )
>>> com = Biskit.Complex( m.takeChains([0]), m.takeChains([1,2]) )
>>> dg = DelphiBindingEnergy( com, protonate=False )
In this case, the original structure would receive a ACE N-terminal
capping of the first chain and the second chain would receive a C-terminal
NME capping residue. The first chain is considered receptor and the second
and third chain are considered ligand.
@see: L{Biskit.PDBCleaner}
@see: L{Biskit.Reduce}
@see: L{Biskit.AtomCharger}
@see: L{Biskit.Delphi}
"""
def __init__(self, com,
protonate=True, addcharge=True,
indi=4.0, exdi=80.0, salt=0.15, ionrad=2, prbrad=1.4,
bndcon=4, scale=2.3, perfil=60,
template=None, topologies=None,
f_charges=None,
verbose=True, debug=False, log=None, tempdir=None, cwd=None,
**kw ):
"""
@param com: complex to analyze
@type com: Biskit.Complex
@param protonate: (re-)build hydrogen atoms with reduce program (True)
see L{Biskit.Reduce}
@type protonate: bool
@param addcharge: Assign partial charges from Amber topologies (True)
@type addcharge: bool
@param indi: interior dilectric (4.0)
@param exdi: exterior dielectric (80.0)
@param salt: salt conc. in M (0.15)
@param ionrad: ion radius (2)
@param prbrad: probe radius (1.4)
@param bndcon: boundary condition (4, delphi default is 2)
@param scale: grid spacing (2.3)
@param perfil: grid fill factor in % (for automatic grid, 60)
@param template: delphi command file template [None=use default]
@type template: str
@param f_radii: alternative delphi atom radii file [None=use default]
@type f_radii: str
@param topologies: alternative list of residue charge/topology files
[default: amber/residues/all*]
@type topologies: [ str ]
@param f_charges: alternative delphi charge file
[default: create custom]
@type f_charges: str
@param kw: additional key=value parameters for Delphi or Executor:
@type kw: key=value pairs
::
debug - 0|1, keep all temporary files (default: 0)
verbose - 0|1, print progress messages to log (log != STDOUT)
node - str, host for calculation (None->local) NOT TESTED
(default: None)
nice - int, nice level (default: 0)
log - Biskit.LogFile, program log (None->STOUT) (default: None)
"""
self.com = com
self.delphicom = None
self.protonate = protonate
self.addcharge = addcharge
## DELPHI run parameters
self.indi=indi # interior dilectric(4.0)
self.exdi=exdi # exterior dielectric(80.0)
self.salt=salt # salt conc. in M (0.15)
self.ionrad=ionrad # ion radius (2)
self.prbrad=prbrad # probe radius (1.4)
self.bndcon=bndcon # boundary condition (4, delphi default is 2)
## DELPHI parameters for custom grid
self.scale=scale # grid spacing (1.2 / A)
self.perfil=perfil # grid fill factor in % (for automatic grid, 60)
## DELPHI parameter file and Amber residue definitions or charge file
self.template = template
self.topologies = topologies
self.f_charges = f_charges
## pump everything else into name space, too
self.__dict__.update( kw )
## prepare globally valid grid
self.grid = None
self.verbose = verbose
self.log = log or StdLog()
self.debug = debug
self.tempdir = tempdir
self.cwd = cwd
self.ezero = self.esalt = None # raw results assigned by run()
def prepare( self ):
"""
"""
mrec = self.com.rec()
mlig = self.com.lig()
m = mrec.concat( mlig )
if self.protonate:
if self.verbose:
self.log.add( '\nRe-building hydrogen atoms...' )
tempdir = self.tempdir
if tempdir:
tempdir += '/0_reduce'
r = Reduce( m, tempdir=tempdir, log=self.log,
autocap=False,
debug=self.debug, verbose=self.verbose )
m = r.run()
if self.addcharge:
if self.verbose:
self.log.add( '\nAssigning charges from Amber topologies...')
ac = AtomCharger( log=self.log, verbose=self.verbose )
ac.charge( m )
mrec = m.takeChains( range( mrec.lenChains() ) )
mlig = m.takeChains( range( mrec.lenChains(), m.lenChains() ) )
self.delphicom = Complex( mrec, mlig )
def setupDelphi( self, model, grid={}, **kw ):
"""
"""
params = copy.copy( self.__dict__ )
params.update( kw )
params['protonate'] = False # run reduce once for complex only
params['addcharge'] = False # run AtomCharger once for complex only
d = Delphi( model, **params )
d.setGrid( **grid )
return d
def processThreesome( self, **kw ):
"""
Calculate Delphi energies for rec, lig and complex
@return: result dictionaries for com, rec, lig
@rtype: ( dict, dict, dict )
"""
dcom = self.setupDelphi( self.delphicom.model(), **kw )
grid = dcom.getGrid()
drec = self.setupDelphi( self.delphicom.rec(), grid=grid, **kw )
dlig = self.setupDelphi( self.delphicom.lig(), grid=grid, **kw )
if self.verbose:
self.log.add('\nrunning Delphi for complex...')
r_com = dcom.run()
if self.verbose:
self.log.add('\nrunning Delphi for receptor...')
r_rec = drec.run()
if self.verbose:
self.log.add('\nrunning Delphi for ligand...')
r_lig = dlig.run()
return r_com, r_rec, r_lig
def processSixsome( self, **kw ):
"""
Calculate Delphi energies for rec, lig and complex with and without
salt.
@return: com, rec, lig delphi calculations with and without ions
@rtype: ( {}, {} )
"""
## with ions
if self.verbose:
self.log.add('\nDelphi calculations with %1.3f M salt' % self.salt)
self.log.add('=======================================')
ri_com, ri_rec, ri_lig = self.processThreesome( salt=self.salt, **kw )
## w/o ions
if self.verbose:
self.log.add('\nDelphi calculations with zero ionic strenght')
self.log.add('==============================================')
r_com, r_rec, r_lig = self.processThreesome( salt=0.0, **kw )
rsalt = { 'com':ri_com, 'rec':ri_rec, 'lig':ri_lig }
rzero = { 'com':r_com, 'rec':r_rec, 'lig':r_lig }
if self.verbose:
self.log.add('\nRaw results')
self.log.add('============')
self.log.add('zero ionic strength: \n' + str(rzero) )
self.log.add('\nwith salt: \n' + str(rsalt) )
return rzero, rsalt
def bindingEnergy( self, ezero, esalt ):
"""
Calculate electrostatic component of the free energy of binding
according to energy partitioning formula.
@param ezero: delphi energies calculated at zero ionic strength
@type ezero: {'com':{}, 'rec':{}, 'lig':{} }
@param esalt: delphi energies calculated with ions (see salt=)
@type esalt: {'com':{}, 'rec':{}, 'lig':{} }
@return: {'dG_kt': free E. in units of kT,
'dG_kcal': free E. in units of kcal / mol,
'dG_kJ': free E. in units of kJ / mol,
'coul': coulomb contribution in kT ,
'solv': solvation contribution in kT,
'ions': salt or ionic contribution in kT }
@rtype: dict { str : float }
"""
delta_0 = {}
delta_i = {}
for k, v in ezero['com'].items():
delta_0[ k ] = ezero['com'][k] - ezero['rec'][k] - ezero['lig'][k]
delta_i[ k ] = esalt['com'][k] - esalt['rec'][k] - esalt['lig'][k]
dG_coul = delta_0['ecoul']
ddG_rxn = delta_0['erxn']
ddG_ions= delta_i['egrid'] - delta_0['egrid']
dG = dG_coul + ddG_rxn + ddG_ions # in units of kT
dG_kcal = round( dG * 0.593, 3) # kcal / mol
dG_kJ = round( dG * 2.479, 3) # kJ / mol
r = {'dG_kt':dG, 'dG_kcal':dG_kcal, 'dG_kJ':dG_kJ,
'coul':dG_coul, 'solv':ddG_rxn, 'ions':ddG_ions}
return r
def run( self ):
"""
Prepare structures and perform Delphi calculations for complex,
receptor and ligand, each with and without ions (salt). Calculate
free energy of binding according to energy partitioning.
Detailed delphi results are saved into object fields 'ezero' and
'esalt' for calculations without and with ions, respectively.
@return: {'dG_kt': free E. in units of kT,
'dG_kcal': free E. in units of kcal / mol,
'dG_kJ': free E. in units of kJ / mol,
'coul': coulomb contribution in kT ,
'solv': solvation contribution in kT,
'ions': salt or ionic contribution in kT }
@rtype: dict { str : float }
"""
self.prepare()
self.ezero, self.esalt = self.processSixsome()
self.result = self.bindingEnergy( self.ezero, self.esalt )
self.delphicom.info['dG_delphi'] = self.result
self.com.info['dG_delphi'] = self.result
for com in [self.delphicom, self.com]:
key = 'delphi_%4.2fsalt' % self.salt
com.rec_model.info[key] = self.esalt['rec']
com.lig_model.info[key] = self.esalt['lig']
com.lig_model.lig_transformed = None
key = 'delphi_0salt'
com.rec_model.info[key] = self.ezero['rec']
com.lig_model.info[key] = self.ezero['lig']
com.lig_model.lig_transformed = None # reset Complex.lig() cache
com.info[key] = self.ezero['com']
return self.result
class DelphiBindingEnergy(object):
"""
Determine the electrostatic component of the free energy of binding using
several rounds of Delphi calculations. DelphiBindingEnergy accepts a
binary complex (L{Biskit.Dock.Complex}) as input, performs several house
keeping tasks (optional capping of free terminals, h-bond optimization and
protonation with the reduce program, assignment of Amber partial atomic
charges) and then calls Delphi six times:
1 - 3: one run each for complex, receptor, and ligand with zero ionic
strength
4 - 6: one run each for complex, receptor, and ligand with custom salt
concentration (default: physiological 0.15 M).
The grid position and dimensions are determined once for the complex and
then kept constant between all runs so that receptor, ligand and complex
calculations can indeed be compared to each other.
The free energy of binding is calculated as described in the Delphi
documentation -- see: delphi2004/examples/binding.html -- according to the
energy partioning scheme:
dG = dG(coulomb) + ddG(solvation) + ddG(ions)
Please have a look at the source code of DelphiBindingEnergy.bindingEnergy()
for a detailed breakup of these terms.
Use:
====
>>> com = Biskit.Complex( 'myrec.pdb', 'mylig.pdb' )
>>> dg = DelphiBindingEnergy( com, verbose=True )
>>> r = dg.run()
Variable r will then receive a dictionary with the free energy of binding
and its three components:
{'dG_kt': free E. in units of kT,
'dG_kcal': free E. in units of kcal / mol,
'dG_kJ': free E. in units of kJ / mol,
'coul': coulomb contribution in kT ,
'solv': solvation contribution in kT,
'ions': salt or ionic contribution in kT }
The modified complex used for the calculation (with hydrogens added and
many other small changes) can be recovered from the DelphiBindingEnergy
instance:
>>> modified_com = dg.delphicom
The run() method assigns the result dictionary to the info record
of both the original and the modified complex. That means:
>>> r1 = com.info['dG_delphi']
>>> r2 = modified_com.info['dG_delphi']
>>> r1 == r2
True
The result of the original DelPhi calculations (with and without salt for
receptor, ligand and complex) are assigned to the info dictionaries of the
complex' receptor and ligand model as well as to the complex itself:
com.info['delphi_0.15salt'] ...delphi run with 0.15M salt on complex
com.info['delphi_0salt'] ...delphi run without salt on complex
com.lig().info['delphi_0.15salt'] ...delphi run with 0.15M salt on ligand
com.lig().info['delphi_0salt'] ...delphi run without salt on ligand
com.rec().info['delphi_0.15salt'] ...delphi run with 0.15M salt on receptor
com.rec().info['delphi_0salt'] ...delphi run without salt on receptor
From there the individual values for solvation, ionic and couloumb
contributions can be recovered. See L{Biskit.Delphi} for a description of
this result dictionary.
Customization:
==============
The most important Delphi parameters (dielectric, salt concentration,
grid scales, ion and probe radius) can be adjusted by passing parameters
to the constructor (see documentation of __init__). The default parameters
should be reasonable. By default,
we create a grid that covers every linear dimension to at least 60%
(perfil=60) and has a density of 2.3 points per Angstroem (scale=2.3).
Such high densities come at much larger computational cost. It is
recommended to test different values and average results.
Note: Any parameters that are not recognized by
DelphiBindingEnergy() will be passed on to the Biskit.Delphi instance
of each Delphi run and, from there, passed on to Biskit.Executor.
The internal pipeline of DelphiBindingEnergy consists of:
* adding hydrogens and capping of protein chain breaks and terminals with
Biskit.Reduce( autocap=True ). The capping is performed by
L{Biskit.PDBCleaner} called from within Reduce.
* mapping Amber partial atomic charges into the structure with
Biskit.AtomCharger()
* setting up the various delphi runs with L{Biskit.Delphi}.
A point worth looking at is the automatic capping of protein chain
breaks and premature terminals with ACE and NME residues. This should
generally be a good idea but the automatic discovery of premature C-termini
or N-termini is guess work at best. See L{Biskit.PDBCleaner} for a more
detailed discussion. You can override the default behaviour by setting
autocap=False (no capping at all, this is now the default) and you can
then provide a complex structure that is already pre-treated by
L{Biskit.Reduce}.
For example:
>>> m = PDBModel('mycomplex.pdb')
>>> m = Reduce( m, capN=[0], capC=[2] )
>>> com = Biskit.Complex( m.takeChains([0]), m.takeChains([1,2]) )
>>> dg = DelphiBindingEnergy( com, protonate=False )
In this case, the original structure would receive a ACE N-terminal
capping of the first chain and the second chain would receive a C-terminal
NME capping residue. The first chain is considered receptor and the second
and third chain are considered ligand.
@see: L{Biskit.PDBCleaner}
@see: L{Biskit.Reduce}
@see: L{Biskit.AtomCharger}
@see: L{Biskit.Delphi}
"""
def __init__(self,
com,
protonate=True,
addcharge=True,
indi=4.0,
exdi=80.0,
salt=0.15,
ionrad=2,
prbrad=1.4,
bndcon=4,
scale=2.3,
perfil=60,
template=None,
topologies=None,
f_charges=None,
verbose=True,
debug=False,
log=None,
tempdir=None,
cwd=None,
**kw):
"""
@param com: complex to analyze
@type com: Biskit.Complex
@param protonate: (re-)build hydrogen atoms with reduce program (True)
see L{Biskit.Reduce}
@type protonate: bool
@param addcharge: Assign partial charges from Amber topologies (True)
@type addcharge: bool
@param indi: interior dilectric (4.0)
@param exdi: exterior dielectric (80.0)
@param salt: salt conc. in M (0.15)
@param ionrad: ion radius (2)
@param prbrad: probe radius (1.4)
@param bndcon: boundary condition (4, delphi default is 2)
@param scale: grid spacing (2.3)
@param perfil: grid fill factor in % (for automatic grid, 60)
@param template: delphi command file template [None=use default]
@type template: str
@param f_radii: alternative delphi atom radii file [None=use default]
@type f_radii: str
@param topologies: alternative list of residue charge/topology files
[default: amber/residues/all*]
@type topologies: [ str ]
@param f_charges: alternative delphi charge file
[default: create custom]
@type f_charges: str
@param kw: additional key=value parameters for Delphi or Executor:
@type kw: key=value pairs
::
debug - 0|1, keep all temporary files (default: 0)
verbose - 0|1, print progress messages to log (log != STDOUT)
node - str, host for calculation (None->local) NOT TESTED
(default: None)
nice - int, nice level (default: 0)
log - Biskit.LogFile, program log (None->STOUT) (default: None)
"""
self.com = com
self.delphicom = None
self.protonate = protonate
self.addcharge = addcharge
## DELPHI run parameters
self.indi = indi # interior dilectric(4.0)
self.exdi = exdi # exterior dielectric(80.0)
self.salt = salt # salt conc. in M (0.15)
self.ionrad = ionrad # ion radius (2)
self.prbrad = prbrad # probe radius (1.4)
self.bndcon = bndcon # boundary condition (4, delphi default is 2)
## DELPHI parameters for custom grid
self.scale = scale # grid spacing (1.2 / A)
self.perfil = perfil # grid fill factor in % (for automatic grid, 60)
## DELPHI parameter file and Amber residue definitions or charge file
self.template = template
self.topologies = topologies
self.f_charges = f_charges
## pump everything else into name space, too
self.__dict__.update(kw)
## prepare globally valid grid
self.grid = None
self.verbose = verbose
self.log = log or StdLog()
self.debug = debug
self.tempdir = tempdir
self.cwd = cwd
self.ezero = self.esalt = None # raw results assigned by run()
def prepare(self):
"""
"""
mrec = self.com.rec()
mlig = self.com.lig()
m = mrec.concat(mlig)
if self.protonate:
if self.verbose:
self.log.add('\nRe-building hydrogen atoms...')
tempdir = self.tempdir
if tempdir:
tempdir += '/0_reduce'
r = Reduce(m,
tempdir=tempdir,
log=self.log,
autocap=False,
debug=self.debug,
verbose=self.verbose)
m = r.run()
if self.addcharge:
if self.verbose:
self.log.add('\nAssigning charges from Amber topologies...')
ac = AtomCharger(log=self.log, verbose=self.verbose)
ac.charge(m)
mrec = m.takeChains(range(mrec.lenChains()))
mlig = m.takeChains(range(mrec.lenChains(), m.lenChains()))
self.delphicom = Complex(mrec, mlig)
def setupDelphi(self, model, grid={}, **kw):
"""
"""
params = copy.copy(self.__dict__)
params.update(kw)
params['protonate'] = False # run reduce once for complex only
params['addcharge'] = False # run AtomCharger once for complex only
d = Delphi(model, **params)
d.setGrid(**grid)
return d
def processThreesome(self, **kw):
"""
Calculate Delphi energies for rec, lig and complex
@return: result dictionaries for com, rec, lig
@rtype: ( dict, dict, dict )
"""
dcom = self.setupDelphi(self.delphicom.model(), **kw)
grid = dcom.getGrid()
drec = self.setupDelphi(self.delphicom.rec(), grid=grid, **kw)
dlig = self.setupDelphi(self.delphicom.lig(), grid=grid, **kw)
if self.verbose:
self.log.add('\nrunning Delphi for complex...')
r_com = dcom.run()
if self.verbose:
self.log.add('\nrunning Delphi for receptor...')
r_rec = drec.run()
if self.verbose:
self.log.add('\nrunning Delphi for ligand...')
r_lig = dlig.run()
return r_com, r_rec, r_lig
def processSixsome(self, **kw):
"""
Calculate Delphi energies for rec, lig and complex with and without
salt.
@return: com, rec, lig delphi calculations with and without ions
@rtype: ( {}, {} )
"""
## with ions
if self.verbose:
self.log.add('\nDelphi calculations with %1.3f M salt' % self.salt)
self.log.add('=======================================')
ri_com, ri_rec, ri_lig = self.processThreesome(salt=self.salt, **kw)
## w/o ions
if self.verbose:
self.log.add('\nDelphi calculations with zero ionic strenght')
self.log.add('==============================================')
r_com, r_rec, r_lig = self.processThreesome(salt=0.0, **kw)
rsalt = {'com': ri_com, 'rec': ri_rec, 'lig': ri_lig}
rzero = {'com': r_com, 'rec': r_rec, 'lig': r_lig}
if self.verbose:
self.log.add('\nRaw results')
self.log.add('============')
self.log.add('zero ionic strength: \n' + str(rzero))
self.log.add('\nwith salt: \n' + str(rsalt))
return rzero, rsalt
def bindingEnergy(self, ezero, esalt):
"""
Calculate electrostatic component of the free energy of binding
according to energy partitioning formula.
@param ezero: delphi energies calculated at zero ionic strength
@type ezero: {'com':{}, 'rec':{}, 'lig':{} }
@param esalt: delphi energies calculated with ions (see salt=)
@type esalt: {'com':{}, 'rec':{}, 'lig':{} }
@return: {'dG_kt': free E. in units of kT,
'dG_kcal': free E. in units of kcal / mol,
'dG_kJ': free E. in units of kJ / mol,
'coul': coulomb contribution in kT ,
'solv': solvation contribution in kT,
'ions': salt or ionic contribution in kT }
@rtype: dict { str : float }
"""
delta_0 = {}
delta_i = {}
for k, v in ezero['com'].items():
delta_0[k] = ezero['com'][k] - ezero['rec'][k] - ezero['lig'][k]
delta_i[k] = esalt['com'][k] - esalt['rec'][k] - esalt['lig'][k]
dG_coul = delta_0['ecoul']
ddG_rxn = delta_0['erxn']
ddG_ions = delta_i['egrid'] - delta_0['egrid']
dG = dG_coul + ddG_rxn + ddG_ions # in units of kT
dG_kcal = round(dG * 0.593, 3) # kcal / mol
dG_kJ = round(dG * 2.479, 3) # kJ / mol
r = {
'dG_kt': dG,
'dG_kcal': dG_kcal,
'dG_kJ': dG_kJ,
'coul': dG_coul,
'solv': ddG_rxn,
'ions': ddG_ions
}
return r
def run(self):
"""
Prepare structures and perform Delphi calculations for complex,
receptor and ligand, each with and without ions (salt). Calculate
free energy of binding according to energy partitioning.
Detailed delphi results are saved into object fields 'ezero' and
'esalt' for calculations without and with ions, respectively.
@return: {'dG_kt': free E. in units of kT,
'dG_kcal': free E. in units of kcal / mol,
'dG_kJ': free E. in units of kJ / mol,
'coul': coulomb contribution in kT ,
'solv': solvation contribution in kT,
'ions': salt or ionic contribution in kT }
@rtype: dict { str : float }
"""
self.prepare()
self.ezero, self.esalt = self.processSixsome()
self.result = self.bindingEnergy(self.ezero, self.esalt)
self.delphicom.info['dG_delphi'] = self.result
self.com.info['dG_delphi'] = self.result
for com in [self.delphicom, self.com]:
key = 'delphi_%4.2fsalt' % self.salt
com.rec_model.info[key] = self.esalt['rec']
com.lig_model.info[key] = self.esalt['lig']
com.lig_model.lig_transformed = None
key = 'delphi_0salt'
com.rec_model.info[key] = self.ezero['rec']
com.lig_model.info[key] = self.ezero['lig']
com.lig_model.lig_transformed = None # reset Complex.lig() cache
com.info[key] = self.ezero['com']
return self.result
cont = com.atomContacts( cutoff=10 ) print cont G.scatter( zip( *N.nonzero( cont ) ) ) # -------------------------- ## ## Visualization ## # how many contacs has each protein residue? com.lig_model['contacts'] = N.sum( cont, axis=0 ) com.rec_model['contacts'] = N.sum( cont, axis=1 ) pm = Pymoler() pm.addPdb( com.rec(), 'rec' ) pm.addPdb( com.lig(), 'lig' ) pm.colorAtoms( 'rec', com.rec()['contacts'] ) pm.colorAtoms( 'lig', com.lig(force=1)['contacts'] ) pm.add( 'show surface') pm.run() ## ## Add external data ## d = PDBDope( com.rec_model ) # d.addConservation()