def saltbridge(poscenter, negcenter, protispos):
"""Detect all salt bridges (pliprofiler between centers of positive and negative charge)"""
data = namedtuple(
'saltbridge',
'positive negative distance protispos resnr restype reschain resnr_l restype_l reschain_l'
)
pairings = []
for pc, nc in itertools.product(poscenter, negcenter):
if not config.MIN_DIST < euclidean3d(
pc.center, nc.center) < config.SALTBRIDGE_DIST_MAX:
continue
resnr = pc.resnr if protispos else nc.resnr
resnr_l = whichresnumber(
nc.orig_atoms[0]) if protispos else whichresnumber(
pc.orig_atoms[0])
restype = pc.restype if protispos else nc.restype
restype_l = whichrestype(
nc.orig_atoms[0]) if protispos else whichrestype(pc.orig_atoms[0])
reschain = pc.reschain if protispos else nc.reschain
reschain_l = whichchain(nc.orig_atoms[0]) if protispos else whichchain(
pc.orig_atoms[0])
contact = data(positive=pc,
negative=nc,
distance=euclidean3d(pc.center, nc.center),
protispos=protispos,
resnr=resnr,
restype=restype,
reschain=reschain,
resnr_l=resnr_l,
restype_l=restype_l,
reschain_l=reschain_l)
pairings.append(contact)
return filter_contacts(pairings)
def hydrophobic_interactions(atom_set_a, atom_set_b):
"""Detection of hydrophobic pliprofiler between atom_set_a (binding site) and atom_set_b (ligand).
Definition: All pairs of qualified carbon atoms within a distance of HYDROPH_DIST_MAX
"""
data = namedtuple(
'hydroph_interaction',
'bsatom bsatom_orig_idx ligatom ligatom_orig_idx '
'distance restype resnr reschain restype_l, resnr_l, reschain_l')
pairings = []
for a, b in itertools.product(atom_set_a, atom_set_b):
if a.orig_idx == b.orig_idx:
continue
e = euclidean3d(a.atom.coords, b.atom.coords)
if not config.MIN_DIST < e < config.HYDROPH_DIST_MAX:
continue
restype, resnr, reschain = whichrestype(a.atom), whichresnumber(
a.atom), whichchain(a.atom)
restype_l, resnr_l, reschain_l = whichrestype(
b.orig_atom), whichresnumber(b.orig_atom), whichchain(b.orig_atom)
contact = data(bsatom=a.atom,
bsatom_orig_idx=a.orig_idx,
ligatom=b.atom,
ligatom_orig_idx=b.orig_idx,
distance=e,
restype=restype,
resnr=resnr,
reschain=reschain,
restype_l=restype_l,
resnr_l=resnr_l,
reschain_l=reschain_l)
pairings.append(contact)
return filter_contacts(pairings)
def halogen(acceptor, donor):
"""Detect all halogen bonds of the type Y-O...X-C"""
data = namedtuple('halogenbond', 'acc acc_orig_idx don don_orig_idx distance don_angle acc_angle restype '
'resnr reschain restype_l resnr_l reschain_l donortype acctype sidechain')
pairings = []
for acc, don in itertools.product(acceptor, donor):
dist = euclidean3d(acc.o.coords, don.x.coords)
if not config.MIN_DIST < dist < config.HALOGEN_DIST_MAX:
continue
vec1, vec2 = vector(acc.o.coords, acc.y.coords), vector(acc.o.coords, don.x.coords)
vec3, vec4 = vector(don.x.coords, acc.o.coords), vector(don.x.coords, don.c.coords)
acc_angle, don_angle = vecangle(vec1, vec2), vecangle(vec3, vec4)
is_sidechain_hal = acc.o.OBAtom.GetResidue().GetAtomProperty(acc.o.OBAtom, 8) # Check if sidechain atom
if not config.HALOGEN_ACC_ANGLE - config.HALOGEN_ANGLE_DEV < acc_angle \
< config.HALOGEN_ACC_ANGLE + config.HALOGEN_ANGLE_DEV:
continue
if not config.HALOGEN_DON_ANGLE - config.HALOGEN_ANGLE_DEV < don_angle \
< config.HALOGEN_DON_ANGLE + config.HALOGEN_ANGLE_DEV:
continue
restype, reschain, resnr = whichrestype(acc.o), whichchain(acc.o), whichresnumber(acc.o)
restype_l, reschain_l, resnr_l = whichrestype(don.orig_x), whichchain(don.orig_x), whichresnumber(don.orig_x)
contact = data(acc=acc, acc_orig_idx=acc.o_orig_idx, don=don, don_orig_idx=don.x_orig_idx,
distance=dist, don_angle=don_angle, acc_angle=acc_angle,
restype=restype, resnr=resnr,
reschain=reschain, restype_l=restype_l,
reschain_l=reschain_l, resnr_l=resnr_l, donortype=don.x.OBAtom.GetType(), acctype=acc.o.type,
sidechain=is_sidechain_hal)
pairings.append(contact)
return filter_contacts(pairings)
def hbonds(acceptors, donor_pairs, protisdon, typ):
"""Detection of hydrogen bonds between sets of acceptors and donor pairs.
Definition: All pairs of hydrogen bond acceptor and donors with
donor hydrogens and acceptor showing a distance within HBOND DIST MIN and HBOND DIST MAX
and donor angles above HBOND_DON_ANGLE_MIN
"""
data = namedtuple('hbond', 'a a_orig_idx d d_orig_idx h distance_ah distance_ad angle type protisdon resnr '
'restype reschain resnr_l restype_l reschain_l sidechain atype dtype')
pairings = []
# DEBUG
if protisdon:
logger.info(f'Ligand has {len(acceptors)} acceptors')
logger.info(f'Prot has {len(donor_pairs)} donor pairs of type {typ}')
else:
logger.info(f'Prot has {len(acceptors)} acceptors')
logger.info(f'Lig has {len(donor_pairs)} donor pairs of type {typ}')
for acc, don in itertools.product(acceptors, donor_pairs):
#if not typ == 'strong':
#continue # keep only the strong hydrogen bonds (default plip version)
# Regular (strong) hydrogen bonds
dist_ah = euclidean3d(acc.a.coords, don.h.coords) # acceptor to H dist
dist_ad = euclidean3d(acc.a.coords, don.d.coords) # acceptor to donor dist
if not config.MIN_DIST < dist_ad < config.HBOND_DIST_MAX:
continue
vec1, vec2 = vector(don.h.coords, don.d.coords), vector(don.h.coords, acc.a.coords)
v = vecangle(vec1, vec2)
if not v > config.HBOND_DON_ANGLE_MIN:
continue
protatom = don.d.OBAtom if protisdon else acc.a.OBAtom
ligatom = don.d.OBAtom if not protisdon else acc.a.OBAtom
is_sidechain_hbond = protatom.GetResidue().GetAtomProperty(protatom, 8) # Check if sidechain atom
resnr = whichresnumber(don.d) if protisdon else whichresnumber(acc.a)
resnr_l = whichresnumber(acc.a_orig_atom) if protisdon else whichresnumber(don.d_orig_atom)
restype = whichrestype(don.d) if protisdon else whichrestype(acc.a)
restype_l = whichrestype(acc.a_orig_atom) if protisdon else whichrestype(don.d_orig_atom)
reschain = whichchain(don.d) if protisdon else whichchain(acc.a)
rechain_l = whichchain(acc.a_orig_atom) if protisdon else whichchain(don.d_orig_atom)
# Next line prevents H-Bonds within amino acids in intermolecular interactions
if config.INTRA is not None and whichresnumber(don.d) == whichresnumber(acc.a):
continue
# Next line prevents backbone-backbone H-Bonds
if config.INTRA is not None and protatom.GetResidue().GetAtomProperty(protatom,
8) and ligatom.GetResidue().GetAtomProperty(
ligatom, 8):
continue
contact = data(a=acc.a, a_orig_idx=acc.a_orig_idx, d=don.d, d_orig_idx=don.d_orig_idx, h=don.h,
distance_ah=dist_ah, distance_ad=dist_ad, angle=v, type=typ, protisdon=protisdon,
resnr=resnr, restype=restype, reschain=reschain, resnr_l=resnr_l,
restype_l=restype_l, reschain_l=rechain_l, sidechain=is_sidechain_hbond,
atype=acc.a.type, dtype=don.d.type)
pairings.append(contact)
return filter_contacts(pairings)
def pistacking(rings_bs, rings_lig):
"""Return all pi-stackings between the given aromatic ring systems in receptor and ligand."""
data = namedtuple(
'pistack',
'proteinring ligandring distance angle offset type restype resnr reschain restype_l resnr_l reschain_l'
)
pairings = []
for r, l in itertools.product(rings_bs, rings_lig):
# DISTANCE AND RING ANGLE CALCULATION
d = euclidean3d(r.center, l.center)
b = vecangle(r.normal, l.normal)
a = min(b, 180 - b if not 180 - b < 0 else
b) # Smallest of two angles, depending on direction of normal
# RING CENTER OFFSET CALCULATION (project each ring center into the other ring)
proj1 = projection(l.normal, l.center, r.center)
proj2 = projection(r.normal, r.center, l.center)
offset = min(euclidean3d(proj1, l.center),
euclidean3d(proj2, r.center))
# RECEPTOR DATA
resnr, restype, reschain = whichresnumber(r.atoms[0]), whichrestype(
r.atoms[0]), whichchain(r.atoms[0])
resnr_l, restype_l, reschain_l = whichresnumber(
l.orig_atoms[0]), whichrestype(l.orig_atoms[0]), whichchain(
l.orig_atoms[0])
# SELECTION BY DISTANCE, ANGLE AND OFFSET
passed = False
if not config.MIN_DIST < d < config.PISTACK_DIST_MAX:
continue
if 0 < a < config.PISTACK_ANG_DEV and offset < config.PISTACK_OFFSET_MAX:
ptype = 'P'
passed = True
if 90 - config.PISTACK_ANG_DEV < a < 90 + config.PISTACK_ANG_DEV and offset < config.PISTACK_OFFSET_MAX:
ptype = 'T'
passed = True
if passed:
contact = data(proteinring=r,
ligandring=l,
distance=d,
angle=a,
offset=offset,
type=ptype,
resnr=resnr,
restype=restype,
reschain=reschain,
resnr_l=resnr_l,
restype_l=restype_l,
reschain_l=reschain_l)
pairings.append(contact)
return filter_contacts(pairings)
def pication(rings, pos_charged, protcharged):
"""Return all pi-Cation interaction between aromatic rings and positively charged groups.
For tertiary and quaternary amines, check also the angle between the ring and the nitrogen.
"""
data = namedtuple(
'pication', 'ring charge distance offset type restype resnr reschain restype_l resnr_l reschain_l protcharged')
pairings = []
if len(rings) == 0 or len(pos_charged) == 0:
return pairings
for ring in rings:
c = ring.center
for p in pos_charged:
d = euclidean3d(c, p.center)
# Project the center of charge into the ring and measure distance to ring center
proj = projection(ring.normal, ring.center, p.center)
offset = euclidean3d(proj, ring.center)
if not config.MIN_DIST < d < config.PICATION_DIST_MAX or not offset < config.PISTACK_OFFSET_MAX:
continue
if type(p).__name__ == 'lcharge' and p.fgroup == 'tertamine':
# Special case here if the ligand has a tertiary amine, check an additional angle
# Otherwise, we might have have a pi-cation interaction 'through' the ligand
n_atoms = [a_neighbor for a_neighbor in OBAtomAtomIter(p.atoms[0].OBAtom)]
n_atoms_coords = [(a.x(), a.y(), a.z()) for a in n_atoms]
amine_normal = np.cross(vector(n_atoms_coords[0], n_atoms_coords[1]),
vector(n_atoms_coords[2], n_atoms_coords[0]))
b = vecangle(ring.normal, amine_normal)
# Smallest of two angles, depending on direction of normal
a = min(b, 180 - b if not 180 - b < 0 else b)
if not a > 30.0:
resnr, restype = whichresnumber(ring.atoms[0]), whichrestype(ring.atoms[0])
reschain = whichchain(ring.atoms[0])
resnr_l, restype_l = whichresnumber(p.orig_atoms[0]), whichrestype(p.orig_atoms[0])
reschain_l = whichchain(p.orig_atoms[0])
contact = data(ring=ring, charge=p, distance=d, offset=offset, type='regular',
restype=restype, resnr=resnr, reschain=reschain,
restype_l=restype_l, resnr_l=resnr_l, reschain_l=reschain_l,
protcharged=protcharged)
pairings.append(contact)
break
resnr = whichresnumber(p.atoms[0]) if protcharged else whichresnumber(ring.atoms[0])
resnr_l = whichresnumber(ring.orig_atoms[0]) if protcharged else whichresnumber(p.orig_atoms[0])
restype = whichrestype(p.atoms[0]) if protcharged else whichrestype(ring.atoms[0])
restype_l = whichrestype(ring.orig_atoms[0]) if protcharged else whichrestype(p.orig_atoms[0])
reschain = whichchain(p.atoms[0]) if protcharged else whichchain(ring.atoms[0])
reschain_l = whichchain(ring.orig_atoms[0]) if protcharged else whichchain(p.orig_atoms[0])
contact = data(ring=ring, charge=p, distance=d, offset=offset, type='regular', restype=restype,
resnr=resnr, reschain=reschain, restype_l=restype_l, resnr_l=resnr_l,
reschain_l=reschain_l, protcharged=protcharged)
pairings.append(contact)
return filter_contacts(pairings)
def metal_complexation(metals, metal_binding_lig, metal_binding_bs):
"""Find all metal complexes between metals and appropriate groups in both protein and ligand, as well as water"""
data = namedtuple(
'metal_complex',
'metal metal_orig_idx metal_type target target_orig_idx target_type '
'coordination_num distance resnr restype '
'reschain restype_l reschain_l resnr_l location rms, geometry num_partners complexnum'
)
pairings_dict = {}
pairings = []
# #@todo Refactor
metal_to_id = {}
metal_to_orig_atom = {}
for metal, target in itertools.product(
metals, metal_binding_lig + metal_binding_bs):
distance = euclidean3d(metal.m.coords, target.atom.coords)
if not distance < config.METAL_DIST_MAX:
continue
if metal.m not in pairings_dict:
pairings_dict[metal.m] = [
(target, distance),
]
metal_to_id[metal.m] = metal.m_orig_idx
metal_to_orig_atom[metal.m] = metal.orig_m
else:
pairings_dict[metal.m].append((target, distance))
for cnum, metal in enumerate(pairings_dict):
rms = 0.0
excluded = []
# cnum +1 being the complex number
contact_pairs = pairings_dict[metal]
num_targets = len(contact_pairs)
vectors_dict = defaultdict(list)
for contact_pair in contact_pairs:
target, distance = contact_pair
vectors_dict[target.atom.idx].append(
vector(metal.coords, target.atom.coords))
# Listing of coordination numbers and their geometries
configs = {
2: [
'linear',
],
3: ['trigonal.planar', 'trigonal.pyramidal'],
4: ['tetrahedral', 'square.planar'],
5: ['trigonal.bipyramidal', 'square.pyramidal'],
6: [
'octahedral',
]
}
# Angle signatures for each geometry (as seen from each target atom)
ideal_angles = {
'linear': [[180.0]] * 2,
'trigonal.planar': [[120.0, 120.0]] * 3,
'trigonal.pyramidal': [[109.5, 109.5]] * 3,
'tetrahedral': [[109.5, 109.5, 109.5, 109.5]] * 4,
'square.planar': [[90.0, 90.0, 90.0, 90.0]] * 4,
'trigonal.bipyramidal':
[[120.0, 120.0, 90.0, 90.0]] * 3 + [[90.0, 90.0, 90.0, 180.0]] * 2,
'square.pyramidal':
[[90.0, 90.0, 90.0, 180.0]] * 4 + [[90.0, 90.0, 90.0, 90.0]],
'octahedral': [[90.0, 90.0, 90.0, 90.0, 180.0]] * 6
}
angles_dict = {}
for target in vectors_dict:
cur_vector = vectors_dict[target]
other_vectors = []
for t in vectors_dict:
if not t == target:
[other_vectors.append(x) for x in vectors_dict[t]]
angles = [
vecangle(pair[0], pair[1])
for pair in itertools.product(cur_vector, other_vectors)
]
angles_dict[target] = angles
all_total = [] # Record fit information for each geometry tested
gdata = namedtuple(
'gdata',
'geometry rms coordination excluded diff_targets') # Geometry Data
# Can't specify geometry with only one target
if num_targets == 1:
final_geom = 'NA'
final_coo = 1
excluded = []
rms = 0.0
else:
for coo in sorted(
configs,
reverse=True): # Start with highest coordination number
geometries = configs[coo]
for geometry in geometries:
signature = ideal_angles[
geometry] # Set of ideal angles for geometry, from each perspective
geometry_total = 0
geometry_scores = [
] # All scores for one geometry (from all subsignatures)
used_up_targets = [
] # Use each target just once for a subsignature
not_used = []
coo_diff = num_targets - coo # How many more observed targets are there?
# Find best match for each subsignature
for subsignature in signature: # Ideal angles from one perspective
best_target = None # There's one best-matching target for each subsignature
best_target_score = 999
for k, target in enumerate(angles_dict):
if target not in used_up_targets:
observed_angles = angles_dict[
target] # Observed angles from perspective of one target
single_target_scores = []
used_up_observed_angles = []
for i, ideal_angle in enumerate(subsignature):
# For each angle in the signature, find the best-matching observed angle
best_match = None
best_match_diff = 999
for j, observed_angle in enumerate(
observed_angles):
if j not in used_up_observed_angles:
diff = abs(ideal_angle -
observed_angle)
if diff < best_match_diff:
best_match_diff = diff
best_match = j
if best_match is not None:
used_up_observed_angles.append(
best_match)
single_target_scores.append(
best_match_diff)
# Calculate RMS for target angles
target_total = sum([
x**2 for x in single_target_scores
])**0.5 # Tot. score targ/sig
if target_total < best_target_score:
best_target_score = target_total
best_target = target
used_up_targets.append(best_target)
geometry_scores.append(best_target_score)
# Total score is mean of RMS values
geometry_total = np.mean(geometry_scores)
# Record the targets not used for excluding them when deciding for a final geometry
[
not_used.append(target) for target in angles_dict
if target not in used_up_targets
]
all_total.append(
gdata(geometry=geometry,
rms=geometry_total,
coordination=coo,
excluded=not_used,
diff_targets=coo_diff))
# Make a decision here. Starting with the geometry with lowest difference in ideal and observed partners ...
# Check if the difference between the RMS to the next best solution is not larger than 0.5
if not num_targets == 1: # Can't decide for any geoemtry in that case
all_total = sorted(all_total, key=lambda x: abs(x.diff_targets))
for i, total in enumerate(all_total):
next_total = all_total[i + 1]
this_rms, next_rms = total.rms, next_total.rms
diff_to_next = next_rms - this_rms
if diff_to_next > 0.5:
final_geom, final_coo, rms, excluded = total.geometry, total.coordination, total.rms, total.excluded
break
elif next_total.rms < 3.5:
final_geom, final_coo, = next_total.geometry, next_total.coordination
rms, excluded = next_total.rms, next_total.excluded
break
elif i == len(all_total) - 2:
final_geom, final_coo, rms, excluded = "NA", "NA", float(
'nan'), []
break
# Record all contact pairing, excluding those with targets superfluous for chosen geometry
only_water = set([x[0].location for x in contact_pairs]) == {'water'}
if not only_water: # No complex if just with water as targets
logger.info(
f'metal ion {metal.type} complexed with {final_geom} geometry (coo. number {final_coo}/ {num_targets} observed)'
)
for contact_pair in contact_pairs:
target, distance = contact_pair
if target.atom.idx not in excluded:
metal_orig_atom = metal_to_orig_atom[metal]
restype_l, reschain_l, resnr_l = whichrestype(
metal_orig_atom), whichchain(
metal_orig_atom), whichresnumber(metal_orig_atom)
contact = data(metal=metal,
metal_orig_idx=metal_to_id[metal],
metal_type=metal.type,
target=target,
target_orig_idx=target.atom_orig_idx,
target_type=target.type,
coordination_num=final_coo,
distance=distance,
resnr=target.resnr,
restype=target.restype,
reschain=target.reschain,
location=target.location,
rms=rms,
geometry=final_geom,
num_partners=num_targets,
complexnum=cnum + 1,
resnr_l=resnr_l,
restype_l=restype_l,
reschain_l=reschain_l)
pairings.append(contact)
return filter_contacts(pairings)
def water_bridges(bs_hba, lig_hba, bs_hbd, lig_hbd, water):
"""Find water-bridged hydrogen bonds between ligand and protein. For now only considers bridged of first degree."""
data = namedtuple(
'waterbridge',
'a a_orig_idx atype d d_orig_idx dtype h water water_orig_idx distance_aw '
'distance_dw d_angle w_angle type resnr restype reschain resnr_l restype_l reschain_l protisdon'
)
pairings = []
# First find all acceptor-water pairs with distance within d
# and all donor-water pairs with distance within d and angle greater theta
lig_aw, prot_aw, lig_dw, prot_hw = [], [], [], []
for w in water:
for acc1 in lig_hba:
dist = euclidean3d(acc1.a.coords, w.oxy.coords)
if config.WATER_BRIDGE_MINDIST <= dist <= config.WATER_BRIDGE_MAXDIST:
lig_aw.append((acc1, w, dist))
for acc2 in bs_hba:
dist = euclidean3d(acc2.a.coords, w.oxy.coords)
if config.WATER_BRIDGE_MINDIST <= dist <= config.WATER_BRIDGE_MAXDIST:
prot_aw.append((acc2, w, dist))
for don1 in lig_hbd:
dist = euclidean3d(don1.d.coords, w.oxy.coords)
d_angle = vecangle(vector(don1.h.coords, don1.d.coords),
vector(don1.h.coords, w.oxy.coords))
if config.WATER_BRIDGE_MINDIST <= dist <= config.WATER_BRIDGE_MAXDIST \
and d_angle > config.WATER_BRIDGE_THETA_MIN:
lig_dw.append((don1, w, dist, d_angle))
for don2 in bs_hbd:
dist = euclidean3d(don2.d.coords, w.oxy.coords)
d_angle = vecangle(vector(don2.h.coords, don2.d.coords),
vector(don2.h.coords, w.oxy.coords))
if config.WATER_BRIDGE_MINDIST <= dist <= config.WATER_BRIDGE_MAXDIST \
and d_angle > config.WATER_BRIDGE_THETA_MIN:
prot_hw.append((don2, w, dist, d_angle))
for l, p in itertools.product(lig_aw, prot_hw):
acc, wl, distance_aw = l
don, wd, distance_dw, d_angle = p
if not wl.oxy == wd.oxy:
continue
# Same water molecule and angle within omega
w_angle = vecangle(vector(acc.a.coords, wl.oxy.coords),
vector(wl.oxy.coords, don.h.coords))
if not config.WATER_BRIDGE_OMEGA_MIN < w_angle < config.WATER_BRIDGE_OMEGA_MAX:
continue
resnr, reschain, restype = whichresnumber(don.d), whichchain(
don.d), whichrestype(don.d)
resnr_l, reschain_l, restype_l = whichresnumber(
acc.a_orig_atom), whichchain(acc.a_orig_atom), whichrestype(
acc.a_orig_atom)
contact = data(a=acc.a,
a_orig_idx=acc.a_orig_idx,
atype=acc.a.type,
d=don.d,
d_orig_idx=don.d_orig_idx,
dtype=don.d.type,
h=don.h,
water=wl.oxy,
water_orig_idx=wl.oxy_orig_idx,
distance_aw=distance_aw,
distance_dw=distance_dw,
d_angle=d_angle,
w_angle=w_angle,
type='first_deg',
resnr=resnr,
restype=restype,
reschain=reschain,
restype_l=restype_l,
resnr_l=resnr_l,
reschain_l=reschain_l,
protisdon=True)
pairings.append(contact)
for p, l in itertools.product(prot_aw, lig_dw):
acc, wl, distance_aw = p
don, wd, distance_dw, d_angle = l
if not wl.oxy == wd.oxy:
continue
# Same water molecule and angle within omega
w_angle = vecangle(vector(acc.a.coords, wl.oxy.coords),
vector(wl.oxy.coords, don.h.coords))
if not config.WATER_BRIDGE_OMEGA_MIN < w_angle < config.WATER_BRIDGE_OMEGA_MAX:
continue
resnr, reschain, restype = whichresnumber(acc.a), whichchain(
acc.a), whichrestype(acc.a)
resnr_l, reschain_l, restype_l = whichresnumber(
don.d_orig_atom), whichchain(don.d_orig_atom), whichrestype(
don.d_orig_atom)
contact = data(a=acc.a,
a_orig_idx=acc.a_orig_idx,
atype=acc.a.type,
d=don.d,
d_orig_idx=don.d_orig_idx,
dtype=don.d.type,
h=don.h,
water=wl.oxy,
water_orig_idx=wl.oxy_orig_idx,
distance_aw=distance_aw,
distance_dw=distance_dw,
d_angle=d_angle,
w_angle=w_angle,
type='first_deg',
resnr=resnr,
restype=restype,
reschain=reschain,
restype_l=restype_l,
reschain_l=reschain_l,
resnr_l=resnr_l,
protisdon=False)
pairings.append(contact)
return filter_contacts(pairings)
