def applyffWater(water, opt):
"""
This function applies the selected force field to the
water
Parameters:
-----------
water: OEMol molecule
The water molecules to parametrize
opt: python dictionary
The options used to parametrize the water
Return:
-------
water_structure: Parmed structure instance
The parametrized water parmed structure
"""
topology, positions = oeommutils.oemol_to_openmmTop(water)
forcefield = app.ForceField(opt['solvent_forcefield'])
unmatched_residues = forcefield.getUnmatchedResidues(topology)
if unmatched_residues:
oechem.OEThrow.Fatal("The following water molecules are not recognized "
"by the selected force field {}: {}".format(opt['solvent_forcefield'], unmatched_residues))
omm_system = forcefield.createSystem(topology, rigidWater=False)
water_structure = parmed.openmm.load_topology(topology, omm_system, xyz=positions)
return water_structure
def test_oemol_to_openmmTop(self):
protein_fn = "tests/data/T4-protein.pdb"
mol = oechem.OEMol()
ifs = oechem.oemolistream(protein_fn)
oechem.OEReadMolecule(ifs, mol)
top, omm_pos = utils.oemol_to_openmmTop(mol)
# Assert Atom numbers
self.assertEqual(top.getNumAtoms(), mol.NumAtoms())
for (op_at, oe_at) in zip(top.atoms(), mol.GetAtoms()):
# Assert atom indexes
self.assertEqual(op_at.index, oe_at.GetIdx())
oe_pos = [v for k, v in mol.GetCoords().items()]
# Assert atom positions
self.assertEqual(oe_pos,
omm_pos.in_units_of(unit.angstrom) / unit.angstrom)
# Assert bond order
bond_mapping = {
app.Single: "Single",
app.Double: "Double",
app.Triple: "Triple",
app.Amide: "Amide",
app.Aromatic: "Aromatic"
}
dic_bond_openmm = dict()
for bond in top.bonds():
# OpenMM atoms
at0_idx = bond[0].index
at1_idx = bond[1].index
oe_bond_type = bond_mapping[bond.type]
if at0_idx < at1_idx:
dic_bond_openmm[(at0_idx, at1_idx)] = (bond.order,
oe_bond_type)
else:
dic_bond_openmm[(at1_idx, at0_idx)] = (bond.order,
oe_bond_type)
dic_bond_oe = dict()
for bond in mol.GetBonds():
# OE atoms
at0_idx = bond.GetBgnIdx()
at1_idx = bond.GetEndIdx()
if at0_idx < at1_idx:
dic_bond_oe[(at0_idx, at1_idx)] = (bond.GetOrder(),
bond.GetType())
else:
dic_bond_oe[(at1_idx, at0_idx)] = (bond.GetOrder(),
bond.GetType())
self.assertEqual(dic_bond_openmm, dic_bond_oe)
def test_improper_pyramidal(verbose=False):
"""Test implement of impropers on ammonia."""
from openeye import oeomega
from openeye import oequacpac
from oeommtools.utils import oemol_to_openmmTop, openmmTop_to_oemol
from openforcefield.utils import get_data_file_path, extractPositionsFromOEMol
# Prepare ammonia
mol = oechem.OEMol()
oechem.OESmilesToMol(mol, 'N')
oechem.OEAddExplicitHydrogens(mol)
omega = oeomega.OEOmega()
omega.SetMaxConfs(100)
omega.SetIncludeInput(False)
omega.SetStrictStereo(False)
# Generate charges
chargeEngine = oequacpac.OEAM1BCCCharges()
status = omega(mol)
oequacpac.OEAssignCharges(mol, chargeEngine)
# Assign atom names
oechem.OETriposAtomTypes(mol)
oechem.OETriposAtomNames(mol)
# Set up minimization
ff = ForceField('test_forcefields/ammonia_minimal.offxml')
topology, positions = oemol_to_openmmTop(mol)
system = ff.createSystem(topology, [mol], verbose=verbose)
positions = extractPositionsFromOEMol(mol)
integrator = openmm.VerletIntegrator(2.0 * unit.femtoseconds)
simulation = app.Simulation(topology, system, integrator)
simulation.context.setPositions(positions)
# Minimize energy
simulation.minimizeEnergy()
state = simulation.context.getState(getEnergy=True, getPositions=True)
energy = state.getPotentialEnergy() / unit.kilocalories_per_mole
newpositions = state.getPositions()
outmol = openmmTop_to_oemol(topology, state.getPositions())
# Sum angles around the N atom
for atom in outmol.GetAtoms(oechem.OEIsInvertibleNitrogen()):
aidx = atom.GetIdx()
nbors = list(atom.GetAtoms())
ang1 = math.degrees(oechem.OEGetAngle(outmol, nbors[0], atom,
nbors[1]))
ang2 = math.degrees(oechem.OEGetAngle(outmol, nbors[1], atom,
nbors[2]))
ang3 = math.degrees(oechem.OEGetAngle(outmol, nbors[2], atom,
nbors[0]))
ang_sum = math.fsum([ang1, ang2, ang3])
# Check that sum of angles around N is within 1 degree of 353.5
if abs(ang_sum - 353.5) > 1.0:
raise Exception(
"Improper torsion for ammonia differs too much from reference partly pyramidal geometry."
"The reference case has a sum of H-N-H angles (3x) at 353.5 degrees; the test case has a sum of {}."
.format(ang_sum))
def applyffProtein(protein, opt):
"""
This function applies the selected force field to the
protein
Parameters:
-----------
protein: OEMol molecule
The protein to parametrize
opt: python dictionary
The options used to parametrize the protein
Return:
-------
protein_structure: Parmed structure instance
The parametrized protein parmed structure
"""
topology, positions = oeommutils.oemol_to_openmmTop(protein)
forcefield = app.ForceField(opt['protein_forcefield'])
unmatched_residues = forcefield.getUnmatchedResidues(topology)
if unmatched_residues:
# Extended ff99SBildn force field
oechem.OEThrow.Info("The following protein residues are not recognized "
"by the selected FF: {} - {}"
"\n...Extended FF is in use".format(opt['protein_forcefield'], unmatched_residues))
ffext_fname = utils.get_data_filename('ComplexPrepCubes', 'ffext/amber99SBildn_ext.xml')
forcefield = app.ForceField()
forcefield.loadFile(ffext_fname)
unmatched_residues = forcefield.getUnmatchedResidues(topology)
if unmatched_residues:
oechem.OEThrow.Fatal("Error. The following protein residues are not recognized "
"by the extended force field {}".format(unmatched_residues))
omm_system = forcefield.createSystem(topology, rigidWater=False)
protein_structure = parmed.openmm.load_topology(topology, omm_system, xyz=positions)
return protein_structure
def test_oemol_to_openmmTop(self):
protein = ommutils.get_data_filename('examples', 'data/T4-protein.pdb')
mol = oechem.OEMol()
ifs = oechem.oemolistream(protein)
oechem.OEReadMolecule(ifs, mol)
top, omm_pos = oeommtools.oemol_to_openmmTop(mol)
# Assert Atom numbers
self.assertEqual(top.getNumAtoms(), mol.NumAtoms())
for (op_at, oe_at) in zip(top.atoms(), mol.GetAtoms()):
# Assert atom indexes
self.assertEqual(op_at.index, oe_at.GetIdx())
oe_pos = [v for k, v in mol.GetCoords().items()]
# Assert atom positions
self.assertEqual(oe_pos,
omm_pos.in_units_of(unit.angstrom) / unit.angstrom)
# Assert bond order
dic_bond_openmm = {}
for bond in top.bonds():
# OpenMM atoms
at0_idx = bond[0].index
at1_idx = bond[1].index
if at0_idx < at1_idx:
dic_bond_openmm[(at0_idx, at1_idx)] = bond.order
else:
dic_bond_openmm[(at1_idx, at0_idx)] = bond.order
dic_bond_oe = {}
for bond in mol.GetBonds():
# OE atoms
at0_idx = bond.GetBgnIdx()
at1_idx = bond.GetEndIdx()
if at0_idx < at1_idx:
dic_bond_oe[(at0_idx, at1_idx)] = bond.GetOrder()
else:
dic_bond_oe[(at1_idx, at0_idx)] = bond.GetOrder()
self.assertEqual(dic_bond_openmm, dic_bond_oe)
def hydrate(system, opt):
"""
This function solvates the system by using PDBFixer
Parameters:
-----------
system: OEMol molecule
The system to solvate
opt: python dictionary
The parameters used to solvate the system
Return:
-------
oe_mol: OEMol
The solvated system
"""
def BoundingBox(molecule):
"""
This function calculates the Bounding Box of the passed
molecule
molecule: OEMol
return: bb (numpy array)
the calculated bounding box is returned as numpy array:
[(xmin,ymin,zmin), (xmax,ymax,zmax)]
"""
coords = [v for k, v in molecule.GetCoords().items()]
np_coords = np.array(coords)
min_coord = np_coords.min(axis=0)
max_coord = np_coords.max(axis=0)
bb = np.array([min_coord, max_coord])
return bb
# Create a system copy
sol_system = system.CreateCopy()
# Calculate system BoundingBox (Angstrom units)
BB = BoundingBox(sol_system)
# Estimation of the box cube length in A
box_edge = 2.0 * opt['solvent_padding'] + np.max(BB[1] - BB[0])
# BB center
xc = (BB[0][0]+BB[1][0])/2.
yc = (BB[0][1]+BB[1][1])/2.
zc = (BB[0][2]+BB[1][2])/2.
delta = np.array([box_edge/2., box_edge/2., box_edge/2.]) - np.array([xc, yc, zc])
sys_coord_dic = {k: (v+delta) for k, v in sol_system.GetCoords().items()}
sol_system.SetCoords(sys_coord_dic)
# Load a fake system to initialize PDBfixer
filename = resource_filename('pdbfixer', 'tests/data/test.pdb')
fixer = PDBFixer(filename=filename)
# Convert between OE and OpenMM topology
omm_top, omm_pos = oeommutils.oemol_to_openmmTop(sol_system)
chain_names = []
for chain in omm_top.chains():
chain_names.append(chain.id)
# Set the correct topology to the fake system
fixer.topology = omm_top
fixer.positions = omm_pos
# Solvate the system
fixer.addSolvent(padding=unit.Quantity(opt['solvent_padding'], unit.angstroms),
ionicStrength=unit.Quantity(opt['salt_concentration'], unit.millimolar))
# The OpenMM topology produced by the solvation fixer has missing bond
# orders and aromaticity. The following section is creating a new openmm
# topology made of just water molecules and ions. The new topology is then
# converted in an OEMol and added to the passed molecule to produce the
# solvated system
wat_ion_top = app.Topology()
# Atom dictionary between the the PDBfixer topology and the water_ion topology
fixer_atom_to_wat_ion_atom = {}
for chain in fixer.topology.chains():
if chain.id not in chain_names:
n_chain = wat_ion_top.addChain(chain.id)
for res in chain.residues():
n_res = wat_ion_top.addResidue(res.name, n_chain)
for at in res.atoms():
n_at = wat_ion_top.addAtom(at.name, at.element, n_res)
fixer_atom_to_wat_ion_atom[at] = n_at
for bond in fixer.topology.bonds():
at0 = bond[0]
at1 = bond[1]
try:
wat_ion_top.addBond(fixer_atom_to_wat_ion_atom[at0],
fixer_atom_to_wat_ion_atom[at1], type=None, order=1)
except:
pass
wat_ion_pos = fixer.positions[len(omm_pos):]
oe_mol = oeommutils.openmmTop_to_oemol(wat_ion_top, wat_ion_pos)
# Setting the box vectors
omm_box_vectors = fixer.topology.getPeriodicBoxVectors()
box_vectors = utils.PackageOEMol.encodePyObj(omm_box_vectors)
oe_mol.SetData(oechem.OEGetTag('box_vectors'), box_vectors)
oechem.OEAddMols(oe_mol, sol_system)
return oe_mol
def applyffExcipients(excipients, opt):
"""
This function applies the selected force field to the
excipients
Parameters:
-----------
excipients: OEMol molecule
The excipients molecules to parametrize
opt: python dictionary
The options used to parametrize the excipients
Return:
-------
excipient_structure: Parmed structure instance
The parametrized excipient parmed structure
"""
# OpenMM topology and positions from OEMol
topology, positions = oeommutils.oemol_to_openmmTop(excipients)
# Try to apply the selected FF on the excipients
forcefield = app.ForceField(opt['protein_forcefield'])
# List of the unrecognized excipients
unmatched_res_list = forcefield.getUnmatchedResidues(topology)
# Unique unrecognized excipient names
templates = set()
for res in unmatched_res_list:
templates.add(res.name)
if templates: # Some excipients are not recognized
oechem.OEThrow.Info("The following excipients are not recognized "
"by the protein FF: {}"
"\nThey will be parametrized by using the FF: {}".format(templates, opt['other_forcefield']))
# Create a bit vector mask used to split recognized from un-recognize excipients
bv = oechem.OEBitVector(excipients.GetMaxAtomIdx())
bv.NegateBits()
# Dictionary containing the name and the parmed structures of the unrecognized excipients
unrc_excipient_structures = {}
# Dictionary used to skip already selected unrecognized excipients and count them
unmatched_excp = {}
# Ordered list of the unrecognized excipients
unmatched_res_order = []
for r_name in templates:
unmatched_excp[r_name] = 0
hv = oechem.OEHierView(excipients)
for chain in hv.GetChains():
for frag in chain.GetFragments():
for hres in frag.GetResidues():
r_name = hres.GetOEResidue().GetName()
if r_name not in unmatched_excp:
continue
else:
unmatched_res_order.append(r_name)
if unmatched_excp[r_name]: # Test if we have selected the unknown excipient
# Set Bit mask
atms = hres.GetAtoms()
for at in atms:
bv.SetBitOff(at.GetIdx())
unmatched_excp[r_name] += 1
else:
unmatched_excp[r_name] = 1
# Create AtomBondSet to extract from the whole excipient system
# the current selected FF unknown excipient
atms = hres.GetAtoms()
bond_set = set()
for at in atms:
bv.SetBitOff(at.GetIdx())
bonds = at.GetBonds()
for bond in bonds:
bond_set.add(bond)
atom_bond_set = oechem.OEAtomBondSet(atms)
for bond in bond_set:
atom_bond_set.AddBond(bond)
# Create the unrecognized excipient OEMol
unrc_excp = oechem.OEMol()
if not oechem.OESubsetMol(unrc_excp, excipients, atom_bond_set):
oechem.OEThrow.Fatal("Is was not possible extract the residue: {}".format(r_name))
# Charge the unrecognized excipient
if not oequacpac.OEAssignCharges(unrc_excp,
oequacpac.OEAM1BCCCharges(symmetrize=True)):
oechem.OEThrow.Fatal("Is was not possible to "
"charge the extract residue: {}".format(r_name))
# If GAFF or GAFF2 is selected as FF check for tleap command
if opt['other_forcefield'] in ['GAFF', 'GAFF2']:
ff_utils.ParamLigStructure(oechem.OEMol(), opt['other_forcefield']).checkTleap
if opt['other_forcefield'] == 'SMIRNOFF':
unrc_excp = oeommutils.sanitizeOEMolecule(unrc_excp)
# Parametrize the unrecognized excipient by using the selected FF
pmd = ff_utils.ParamLigStructure(unrc_excp, opt['other_forcefield'],
prefix_name=opt['prefix_name']+'_'+r_name)
unrc_excp_struc = pmd.parameterize()
unrc_excp_struc.residues[0].name = r_name
unrc_excipient_structures[r_name] = unrc_excp_struc
# Recognized FF excipients
pred_rec = oechem.OEAtomIdxSelected(bv)
rec_excp = oechem.OEMol()
oechem.OESubsetMol(rec_excp, excipients, pred_rec)
if rec_excp.NumAtoms() > 0:
top_known, pos_known = oeommutils.oemol_to_openmmTop(rec_excp)
ff_rec = app.ForceField(opt['protein_forcefield'])
try:
omm_system = ff_rec.createSystem(top_known, rigidWater=False)
rec_struc = parmed.openmm.load_topology(top_known, omm_system, xyz=pos_known)
except:
oechem.OEThrow.Fatal("Error in the recognised excipient parametrization")
# Unrecognized FF excipients
bv.NegateBits()
pred_unrc = oechem.OEAtomIdxSelected(bv)
unrc_excp = oechem.OEMol()
oechem.OESubsetMol(unrc_excp, excipients, pred_unrc)
# Unrecognized FF excipients coordinates
oe_coord_dic = unrc_excp.GetCoords()
unrc_coords = np.ndarray(shape=(unrc_excp.NumAtoms(), 3))
for at_idx in oe_coord_dic:
unrc_coords[at_idx] = oe_coord_dic[at_idx]
# It is important the order used to assemble the structures. In order to
# avoid mismatch between the coordinates and the structures, it is convenient
# to use the unrecognized residue order
unmatched_res_order_count = []
i = 0
while i < len(unmatched_res_order):
res_name = unmatched_res_order[i]
for j in range(i+1, len(unmatched_res_order)):
if unmatched_res_order[j] == res_name:
continue
else:
break
if i == (len(unmatched_res_order) - 1):
num = 1
unmatched_res_order_count.append((res_name, num))
break
else:
num = j - i
unmatched_res_order_count.append((res_name, num))
i = j
# Merge all the unrecognized Parmed structure
unrc_struc = parmed.Structure()
for pair in unmatched_res_order_count:
res_name = pair[0]
nums = pair[1]
unrc_struc = unrc_struc + nums*unrc_excipient_structures[res_name]
# Set the unrecognized coordinates
unrc_struc.coordinates = unrc_coords
# Set the parmed excipient structure merging
# the unrecognized and recognized parmed
# structures together
if rec_excp.NumAtoms() > 0:
excipients_structure = unrc_struc + rec_struc
else:
excipients_structure = unrc_struc
return excipients_structure
else: # All the excipients are recognized by the selected FF
omm_system = forcefield.createSystem(topology, rigidWater=False)
excipients_structure = parmed.openmm.load_topology(topology, omm_system, xyz=positions)
return excipients_structure
def solvate(system, opt):
"""
This function solvates the system by using PDBFixer
Parameters:
-----------
system: OEMol molecule
The system to solvate
opt: python dictionary
The parameters used to solvate the system
Return:
-------
oe_mol: OEMol
The solvated system
"""
# Load a fake system to initialize PDBfixer
filename = resource_filename('pdbfixer', 'tests/data/test.pdb')
fixer = PDBFixer(filename=filename)
# Convert between OE and OpenMM topology
omm_top, omm_pos = oeommutils.oemol_to_openmmTop(system)
chain_names = []
for chain in omm_top.chains():
chain_names.append(chain.id)
# Set the correct topology to the fake system
fixer.topology = omm_top
fixer.positions = omm_pos
# Solvate the system
fixer.addSolvent(padding=unit.Quantity(opt['solvent_padding'], unit.angstroms),
ionicStrength=unit.Quantity(opt['salt_concentration'], unit.millimolar))
# The OpenMM topology produced by the solvation fixer has missing bond
# orders and aromaticity. The following section is creating a new openmm
# topology made of just water molecules and ions. The new topology is then
# converted in an OEMol and added to the passed molecule to produce the
# solvated system
wat_ion_top = app.Topology()
# Atom dictionary between the the PDBfixer topology and the water_ion topology
fixer_atom_to_wat_ion_atom = {}
for chain in fixer.topology.chains():
if chain.id not in chain_names:
n_chain = wat_ion_top.addChain(chain.id)
for res in chain.residues():
n_res = wat_ion_top.addResidue(res.name, n_chain)
for at in res.atoms():
n_at = wat_ion_top.addAtom(at.name, at.element, n_res)
fixer_atom_to_wat_ion_atom[at] = n_at
for bond in fixer.topology.bonds():
at0 = bond[0]
at1 = bond[1]
try:
wat_ion_top.addBond(fixer_atom_to_wat_ion_atom[at0],
fixer_atom_to_wat_ion_atom[at1], type=None, order=1)
except:
pass
wat_ion_pos = fixer.positions[len(omm_pos):]
oe_mol = oeommutils.openmmTop_to_oemol(wat_ion_top, wat_ion_pos)
# Setting the box vectors
omm_box_vectors = fixer.topology.getPeriodicBoxVectors()
box_vectors = utils.PackageOEMol.encodePyObj(omm_box_vectors)
oe_mol.SetData(oechem.OEGetTag('box_vectors'), box_vectors)
oechem.OEAddMols(oe_mol, system)
return oe_mol
