Lactoferrin–metal interactions: first crystal structure of a complex of lactoferrin with a lanthanide ion (Sm3+) at 3.4 Å resolution

1999 ◽  
Vol 55 (11) ◽  
pp. 1799-1804 ◽  
Author(s):  
Ashwani K. Sharma ◽  
Tej P. Singh

Lactoferrin is an important member of the transferrin family. A characteristic property of transferrins is their ability to bind very tightly (K app ≃ 1020) but reversibly two Fe3+ ions. The structural consequences of binding a metal other than Fe3+ have been examined by crystallographic analysis at 3.4 Å resolution of mare samarium–lactoferrin (Sm2Lf). The structure was refined to an R factor of 0.219 for 8776 reflections in the resolution range 17.0–3.4 Å. The samarium geometry (distorted octahedral coordination) is similar in both lobes. However, the anion interactions are quite different in the two lobes. In the N lobe, the anion is able to form only two hydrogen bonds instead of the four observed in the C lobe of Sm2Lf and the six observed in Fe2Lf. This is because Arg121, Thr117 and Gly124 have moved away from the anion as a consequence of the binding of the Sm3+ ion. The protein ligands in the binding cleft of Sm2Lf show large displacements, but the overall protein structure remains the same. The binding of Sm3+ by lactoferrin shows that the protein is capable of sequestering ions of different sizes and charges, though with reduced affinity. This conclusion should be true of other transferrins also.

2016 ◽  
Vol 72 (12) ◽  
pp. 1683-1686 ◽  
Author(s):  
Iuliia Shatrava ◽  
Kateryna Gubina ◽  
Vladimir Ovchynnikov ◽  
Viktoriya Dyakonenko ◽  
Vladimir Amirkhanov

In the molecular structure of the title compound, [CaNa(C10H20Cl3N3O2P)3(H2O)], the Ca2+ion has a slightly distorted octahedral coordination environment defined by six O atoms which belong to the carbonyl and phosphoryl groups of the three coordinating ligands. Two Cl atoms of CCl3groups and four O atoms form the coordination environment of the Na+ion: three from the carbonyl groups of ligands and one O atom from a coordinating water molecule. In the crystal, the bimetallic complexes are assembled into chains along thec-axis directionviaO—H...O hydrogen bonds that involve the coordinating water molecules and the phosphoryl groups.


Author(s):  
Matthias Weil ◽  
Théo Veyer

A new form of NaMnAsO4, sodium manganese(II) orthoarsenate, has been obtained under hydrothermal conditions, and is referred to as the β-polymorph. In contrast to the previously reported orthorhombic α-polymorph that crystallizes in the olivine-type of structure and has one manganese(II) cation in a distorted octahedral coordination, the current β-polymorph contains two manganese(II) cations in [5]-coordination, intermediate between a square-pyramid and a trigonal bipyramid. In the crystal structure of β-NaMnAsO4, four [MnO5] polyhedra are linked through vertex- and edge-sharing into finite {Mn4O16} units strung into rows parallel to [100]. These units are linked through two distinct orthoarsenate groups into a framework structure with channels propagating parallel to the manganese oxide rows. Both unique sodium cations are situated inside the channels and exhibit coordination numbers of six and seven. β-NaMnAsO4 is isotypic with one form of NaCoPO4 and with NaCuAsO4.


2017 ◽  
Vol 73 (10) ◽  
pp. 1520-1522 ◽  
Author(s):  
Joseph Ring ◽  
Lorenz Lindenthal ◽  
Matthias Weil ◽  
Berthold Stöger

Single crystals of the title compound, Na(H2AsO4), were obtained by partial neutralization of arsenic acid with sodium hydroxide in aqueous solution. The crystal structure of Na(H2AsO4) is isotypic with the phosphate analogue and the asymmetric unit consists of two sodium cations and two tetrahedral H2AsO4−anions. Each of the sodium cations is surrounded by six O atoms of five H2AsO4−groups, defining distorted octahedral coordination spheres. In the extended structure, the sodium cations and dihydrogen arsenate anions are arranged in the form of layers lying parallel to (010). Strong hydrogen bonds [range of O...O distances 2.500 (3)–2.643 (3) Å] between adjacent H2AsO4−anions are observed within and perpendicular to the layers. The isotypic structure of Na(H2PO4) is comparatively discussed.


Author(s):  
Bougar Sarr ◽  
Abdou Mbaye ◽  
Cheikh Abdoul Khadir Diop ◽  
Mamadou Sidibe ◽  
Yoann Rousselin

The organic–inorganic title salt, (C6H16N)2[Sn(C2O4)2Cl2] or ( i Pr2NH2)2[Sn(C2O4)2Cl2], was obtained by reacting bis(diisopropylammonium) oxalate with tin(IV) chloride dihydrate in methanol. The SnIV atom is coordinated by two chelating oxalate ligands and two chloride ions in cis positions, giving rise to an [Sn(C2O4)2Cl2]2− anion (point group symmetry 2), with the SnIV atom in a slightly distorted octahedral coordination. The cohesion of the crystal structure is ensured by the formation of N—H...O hydrogen bonding between (iPr2NH2)+ cations and [SnCl2(C2O4)2]2− anions. This gives rise to an infinite chain structure extending parallel to [101]. The main inter-chain interactions are van der Waals forces. The electronic spectrum of the title compound displays only one high intensity band in the UV region assignable to ligand–metal ion charge-transfer (LMCT) transitions. An IR spectrum was also recorded and is discussed.


2017 ◽  
Vol 73 (9) ◽  
pp. 1302-1304 ◽  
Author(s):  
Hicham El Hamdani ◽  
Mohammed El Amane ◽  
Carine Duhayon

The title complex, [Co(C7H7N4O2)2(H2O)4], comprises mononuclear molecules consisting of a CoIIion, two deprotonated theophylline ligands (systematic name: 1,3-dimethyl-7H-purine-2,6-dione) and four coordinating water molecules. The CoIIatom lies on an inversion centre and has a slightly distorted octahedral coordination environment, with two N atoms of twotrans-oriented theophylline ligands and the O atoms of four water molecules. An intramolecular hydrogen bond stabilizes this conformation. A three-dimensional supramolecular network structure is formed by intermolecular O—H...O and O—H...N hydrogen bonds.


1986 ◽  
Vol 41 (10) ◽  
pp. 1191-1195 ◽  
Author(s):  
Ute Patt-Siebel ◽  
Somluck Ruangsuttinarupap ◽  
Ulrich Müller ◽  
Jürgen Pebler ◽  
Kurt Dehnicke

S5N5[SnCl5(CH3CN)] is prepared by the reaction of SnCl2 with trithiazyl chloride in acetonitrile suspension. The compound is characterized by its IR spectrum, the 119Sn Mössbauer spectrum and by an X-ray crystal structure determination (1851 observed, independent reflexions, R = 0.024). S5N5[SnCl5(CH3CN)] crystallizes in the monoclinic space group P21/n with Z = 4 and the lattice dimensions a = 758.8; b = 1574.6; c = 1429.1 pm; β = 97.65°. The compound consists of planar S5N5® cations with the azulene-like structure, and anions [SnCl5(CH3CN)]e in which the tin atom has a distorted octahedral coordination. The bond angle Sn-N ≡ C (168°) is surprisingly small.


1977 ◽  
Vol 32 (11) ◽  
pp. 1356-1357 ◽  
Author(s):  
Klaus-Jürgen Range ◽  
Fritz Ketterl

A compound Cu3TiO4 was found to exist in the ternary system CuO-Cu2O-TiO2. The crystal structures of two modifications are very similar and contain Cu+ with linear, Cu2+ and Ti4+ with trigonal distorted octahedral coordination.


1985 ◽  
Vol 40 (10) ◽  
pp. 1314-1319 ◽  
Author(s):  
Heribert Wadle ◽  
Kurt Dehnicke ◽  
Dieter Fenske

Trithiazylchloride, (NSCl)3, reacts with metallic chromium, with chromium hexacarbonyl, with CrCl3·3 thf, as well as with chromium(VI) oxide to form mixtures, in which S4N3⊕ [CrCl4(N2S2)]⊖ can be identified as the major product. This compound reacts with tetraphenylarsonium chloride in dichloromethane to form the title compound, which we have characterized by IR spectroscopy and an X-ray crystal structural analysis. (AsPh4)4[CrCl4(N2S2)]4·8 CH2Cl2 crystallizes monoclinically in the space group C2/c with four formula units per unit cell and with the following lattice constants at -100 °C: a = 2146, b = 2033, c = 3137 pm; β = 96.0° (9918 independent observed reflexions, R = 0.064). The compound consists of AsPh4⊕ ions, tetrameric anions [CrCl4(N2S2)]44⊖ and included CH2Cl2 molecules. The chromium atoms of the anions occupy the corners of a nearly ideal square; they are connected via the N-atoms of planar N2S2-rings, which are oriented perpendicularly to the Cr4-plane. The chromium atoms complete their distorted octahedral coordination with four terminal chlorine atoms, the axial ones of which form short Cl···S-contacts of average 310 pm to the S-atoms of the N2S2-rings.


Author(s):  
Edith Dimitri Djomo ◽  
Frédéric Capet ◽  
Justin Nenwa ◽  
Michel M. Bélombé ◽  
Michel Foulon

The FeIIIions in the hybrid title salt, (C7H11N2)[Fe(C2O4)2(H2O)2]·0.5H2O, show a distorted octahedral coordination environment, with four O atoms from two chelating oxalate dianions and two O atoms from twocisaqua ligands. The average Fe—O(oxalate) bond length [2.00 (2) Å] is shorter than the average Fe—O(water) bond length [2.027 (19) Å]. The ionic components are connectedviaintermolecular N—H...O and O—H...O hydrogen bonds into a three-dimensional network.


Author(s):  
Yukiko Yamaguchi-Terasaki ◽  
Takashi Fujihara ◽  
Akira Nagasawa ◽  
Sumio Kaizaki

In the neutral complex molecule of the title compound,fac-[CrCl3(tpa)] [tpa is tris(pyridin-2-yl)amine; C15H12N4], the CrIIIion is bonded to three N atoms that are constrained to afacialarrangement by the tpa ligand and by three chloride ligands, leading to a distorted octahedral coordination sphere. The average Cr—N and Cr—Cl bond lengths are 2.086 (5) and 2.296 (4) Å, respectively. The complex molecule is located on a mirror plane. In the crystal, a combination of C—H...N and C—H...Cl hydrogen-bonding interactions connect the molecules into a three-dimensional network.


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