Authors: Avazbek Ibragimov

During systematic investigations of bioavailability and biological action enhancement of well known compounds with low bioactivity, a new mixed-ligand metal complex, [Cd(DNBA)(en))] (DNBA = 3,5-di-nitro-benzoate, CHNO; en = ethyl-endi-amine, CHN), has been synthesized. The complex mol-ecules are located on inversion centers. Two DNBA anions monodentately coordinate the Cd atom through an oxygen atom of the carboxyl-ate group while two en mol-ecules coordinate in a chelate fashion, resulting in a distorted ON coordination set. There is a weak intra-molecular hydrogen bond of 3.099 (4) Å between the non-coordinating oxygen atom of the carboxyl-ate group and one of the en amine groups. Three relatively weak inter-molecular N-H⋯O hydrogen bonds associate complex mol-ecules into sheets extending parallel to (01), which are further stabilized by - inter-actions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯O/O⋯H (50.2%) and H⋯H (21.1%) inter-actions.

PubMed: 36339790
DOI: 10.1107/S2414314620008433

Authors: Rehana Akram, Waseeq Ahmad Siddiqui, M Nawaz Tahir...

In the title compound, [Mn(C(7)H(6)NO(4)S)(2)(H(2)O)(4)], the Mn atom, lying on an inversion center, exhibits a distorted octa-hedral coordination by six O atoms, two from carboxyl-ate groups and four from water mol-ecules. The SO(2)NH(2) group is involved in a three dimensional polymeric hydrogen bonding network along with the water mol-ecules. π-Stacking inter-actions parallel to the c axis lead to a separation of 4.0050 (12) Å between the centroids of the benzene rings.

PubMed: 21201036
DOI: 10.1107/S1600536808029450

Authors: Hong-Ren Chen, Tian-Sheng Tang, Jin Wang...

The title coordination polymer, {[Nd(2)(C(4)H(2)O(4))(3)(H(2)O)(4)]·3H(2)O}, was synthesized by the reaction of neodymium(III) nitrate hexa-hydrate with fumaric acid in a water-methanol (7:3) solution. The asymmetric unit comprises two Nd(3+) cations, three fumarate dianions (L(2-)), four aqua ligands and three uncoordinated water mol-ecules. The carboxyl-ate groups of the fumarate dianions exhibit different coordination modes. In one fumarate dianion, two carboxyl-ate groups chelate two Nd(3+) cations, while one of the O atoms is coordinated to another Nd(3+) cation. Another fumarate dianion bridges three Nd(3+) cations: one of the carboxyl-ate groups chelates one Nd(3+) cation, while the other carboxyl-ate group bridges two Nd(3+) cations in a monodentate mode. The third fumarate dianion bridges four Nd(3+) cations, where one of the carboxyl-ate groups chelates one Nd(3+) cation and coordinates in a monodentate mode to a second Nd(3+), while the second carboxyl-ate groups bridges two Nd(3+) cations in a monodentate mode and one O atom is coordinated to one Nd(3+) cation. The Nd(3+) cations are in a distorted tricapped-trigonal prismatic environment and coordinated by seven O atoms from the fumarate ligands and two O atoms from water mol-ecules. The Nd(3+) cations are linked by two carboxyl-ate O atoms and two carboxyl-ate groups, generating infinite Nd-O chains to form a three-dimensional framework. There are O-H⋯O and C-H⋯O hydrogen-bonding interactions between the coordin-ated and uncoordinated water mol-ecules and carboxyl-ate O atoms.

PubMed: 22199526
DOI: 10.1107/S1600536811046447

Authors: Shi-Jie Li, Juan-Hua Liu, Wen-Dong Song...

In the title compound, C(7)H(8)N(2)O(4)·H(2)O, the imidazole N atom is protonated and one of the carboxyl-ate groups is deprontonated, forming a zwitterion. The two carboxyl groups are are approximately coplanar with the imidazole ring [O-C-C-C torsion angles = -176.8 (2) and 2.9 (4)° for one group and -4.6 (3) and 176.4 (2)° for the other] and have an intra-molecular O-H⋯O hydrogen bond between them. The water mol-ecule is linked to the organic mol-ecules via an N-H⋯O hydrogen bonds. Inter-molecular O-H⋯O and N-H⋯O hydrogen bonds are found in the crystal structure.

PubMed: 21754252
DOI: 10.1107/S1600536811010774

Authors: Hao Zhang, Wei Shen, Don Rempel...

Her4 is a transmembrane receptor tyrosine kinase belonging to the ErbB-EGFR family. It plays a vital role in the cardiovascular and nervous systems, and mutations in Her4 have been found in melanoma and lung cancer. The kinase domain of Her4 forms a dimer complex, called the asymmetric dimer, which results in kinase activation. Although a crystal structure of the Her4 asymmetric dimer is known, the dimer affinity and the effect of the subsequent phosphorylation steps on kinase domain conformation are unknown. We report here the use of carboxyl-group footprinting MS on a recombinant expressed, Her4 kinase-domain construct to address these questions. Carboxyl-group footprinting uses a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, in the presence of glycine ethyl ester, to modify accessible carboxyl groups on glutamate and aspartate residues. Comparisons of Her4 kinase-domain monomers versus dimers and of unphosphorylated versus phosphorylated dimers were made to map the dimerization interface and to determine phosphorylation induced-conformational changes. We detected 37 glutamate and aspartate residues that were modified, and we quantified their extents of modification by liquid chromatography MS. Five residues showed changes in carboxyl-group modification. Three of these residues are at the predicted dimer interface, as shown by the crystal structure, and the remaining two residues are on loops that likely have altered conformation in the kinase dimer. Incubating the Her4 kinase dimers with ATP resulted in dramatic increase in Tyr-850 phosphorylation, located on the activation loop, and this resulted in a conformational change in this loop, as evidenced by reduction in carboxyl-group modification. The kinase monomer-dimer equilibrium was measured using a titration format in which the extent of carboxyl-group footprinting was mathematically modeled to give the dimer association constant (1.5-6.8 × 10(12) dm(2)/mol). This suggests that the kinase-domain makes a significant contribution to the overall dimerization affinity of the full-length Her4 protein.

Topics: Carboxylic Acids; ErbB Receptors; Humans; Phosphorylation; Protein Conformation; Protein Interaction Domains and Motifs; Protein Multimerization; Receptor, ErbB-4; Recombinant Proteins; Spectrometry, Mass, Electrospray Ionization; Tandem Mass Spectrometry; Titrimetry

PubMed: 21422241
DOI: 10.1074/mcp.M110.005678

Authors: René Faure, Nuria A Illán-Cabeza, Sonia B Jiménez-Pulido...

In the title compound, C(10)H(10)N(4)O(4)·0.5H(2)O, the two rings of the pteridine system are nearly coplanar [dihedral angle = 4.25 (9)°]. The atoms of the carboxyl group are also coplanar with the pteridine unit [r.m.s. deviation from the mean plane of the pteridine skeleton = 0.092 (2) Å]. In the crystal, the presence of the water molecule of crystallization (O atom site symmetry 2) leads to a hydrogen-bonding pattern different from the one shown by many carboxylic acid compounds (dimers formed through O-H⋯O hydrogen bonds between neighbouring carboxyl groups): in the present structure, the water mol-ecule, which lies on a binary axis, acts as a bridge between two mol-ecules, forming a hydrogen-bonded dimer. In addition to the hydrogen bonds, there are π-π ring stacking inter-actions involving the pyrimidine and pyrazine rings [centroid-centroid distance = 3.689 (1)Å], and two different pyrazine rings [centroid-centroid distance = 3.470 (1)Å]. Finally, there is a C-O⋯π contact involving a carboxyl-ate C-O and the pyrimidine ring with a short O⋯Cg distance of 2.738 (2) Å.

PubMed: 21580456
DOI: 10.1107/S1600536810007166

Authors: Moon-Hwan Kim, Hee-Moon Park, Chong-Hyeak Kim...

In the title compound, C(31)H(29)NO(5), the methyl carboxyl-ate and dimethyl-amino groups on the naphtho-pyran group are almost coplanar with the naphtho-pyran ring system [r.m.s. deviations = 0.08 (2) and 0.161 (2) Å, respectively]. The dihedral angle between the methyl carboxyl-ate and dimethyl-amino groups is 4.9 (1)°. The pyran ring has an envelope conformation with the quaternary C atom out of plane by 0.4739 (13) Å. The meth-oxy-phenyl substituent forms a dihedral angle of 16.6 (1)° with the plane of the benzene ring, while the other meth-oxy-phenyl group is almost coplanar, making a dihedral angle of 1.4 (1)°.

PubMed: 21754239
DOI: 10.1107/S160053681101049X

Authors: Jin-Li Qi, Wei Xu

The title mononuclear Cu(II) complex, [Cu(C(8)H(5)O(3))(2)(C(10)H(8)N(2))], is comprised of a Cu(II) cation, two 4-formyl-benzoate (L(-)) ligands and a 2,2'-bipyridine (bipy) ligand. The Cu(II) ion and bipy ligand lie on a crystallographic twofold rotation axis; the Cu(II) ion is coordinated by two N atoms from one bipy ligand and two O atoms from two different carboxyl-ate groups of two L(-) ligands, exhibiting effectively a distorted square-planar geometry. The complex mol-ecules are inter-linked to generate two-dimensional supra-molecular layers in the ab plane, formed by C-H⋯O hydrogen bonds, where the O acceptor is the O atom from the carboxyl-ate group not involved in coordination to the Cu(II) ion. The two-dimensional layers are stacked in a sequence via C-H⋯O hydrogen-bonding inter-actions where the formyl O atom acts as acceptor.

PubMed: 22904733
DOI: 10.1107/S1600536812031066

Authors: Rafiqa A Alieva, Vusala I Mardanova, Famil M Chyraqov...

In the title compound, [Cu(C(12)H(11)N(2)O(4))(2)(C(10)H(14)N(2)O)(2)(H(2)O)(2)], the Cu(II) atom lies on a center of inversion and is coordinated by carboxyl-ate O atoms, pyridine N atoms and two water mol-ecules in an elongated octa-hedral geometry. The pyridine ring is oriented at a dihedral angle of 74.83 (12)° with respect to the benzene ring. Intra-molecular O-H⋯O and N-H⋯O hydrogen bonding is observed. The water mol-ecule is a hydrogen-bond donor to the carbonyl O atom of an adjacent carboxyl-ate group, generating a chain running along the a axis. One of the ethyl groups is disordered over two sets of sites in a 0.787 (5):0.213 ratio.

PubMed: 22346813
DOI: 10.1107/S1600536811056200