Diversity Of Structural Motifs Research Articles

New Insights from Crystallographic Data: Diversity of Structural Motifs and Molecular Recognition Properties between Groups of IDO1 Structures.

A large number of crystallographic structures of IDO1 in different ligand-bound and -unbound states have been disclosed over the last decade. Yet, only a few of them have been exploited for structure-based drug design (SBDD) campaigns. In this study, we analyzed the structural motifs and molecular-recognition properties of three groups of IDO1 structures: 1) structures containing the heme group and inhibitors in the catalytic site; 2) heme-free structures of IDO1; 3) substrate-bound structures of IDO1. The results suggest that unrelated conformations of the enzyme have been solved with different ligand-induced changes of secondary motifs that localize even in regions remote from the catalytic site. Moreover, the study identified an uncharted region of molecular-recognition space covered by IDO1 binding sites that could guide the selection of diverse structures for additional SBDD studies aimed at the identification of novel lead compounds with differentiated chemical scaffolds.

The pH-Controlled Hydrothermal Synthesis and Crystal Structure of Two Novel Phosphomolybdate Derivatives

Two novel phosphomolybdate derivatives, (H2en)(Hen)2(H2P2Mo5O23)·5H2O (1) and [Cu(phen)(en)][Cu(phen)(en)(H2O)]2[PMo 8 VI Mo 4 V O40{Cu(phen)}2]2·6H2O (2) (en = ethylenediamine, phen = 1,10′-phenanthroline), were synthesized under hydrothermal technique and characterized by crystal X-ray diffraction analysis, elemental analysis, IR and TGA. Compound 1 is constructed from a [H2P2Mo5O23]4− polyoxoanion and one (H2en)2+ cation and two (Hen)+ cations and is a typical Strandberg-type hepteropoly compound. The interaction force between the components are electrostatic force and hydrogen bonds which involve polyoxoanions, water molecules and ethylenediammonium cations. Compound 2 consists of one [Cu(phen)(en)]2+ and two [Cu(phen)(en)(H2O)]2+ cations and two [PMo 8 VI Mo 4 V O40{Cu(phen)}2]3− polyoxoanions. The reduced Keggin polyoxoanion [PMo 8 VI Mo 4 V O40]7− of 2 is capped by two divalent Cu atoms through four bridging oxo groups on two opposite {Mo4O4} faces. The results reveal that the pH plays a significant role in promoting the diversity of structural motifs. The effect of en is not only to ensure the required amounts of ligands for the reaction process, but also to control the pH. In the synthetic process, the control of the reaction conditions plays a crucial role in constructing different structures.

Azole derivatives as histamine H 3 receptor antagonists, Part I: Thiazol-2-yl ethers

Most human histamine H 3 receptor ( hH 3R) antagonists follow a general structural blueprint, containing a basic moiety linked by a spacer to a substituted core element. In this investigation the acceptance of thiazol-2-yl ether moieties in the core region is proved with some ether derivatives showing hH 3R binding affinities in the nanomolar concentration range. A diversity of structural motifs is used as substituents to enhance the in vitro hH 3R binding affinity.

Lower Main-Group Element Complexes with a Soft Scorpionate Ligand: The Structural Influence of Stereochemically Active Lone Pairs

The syntheses and structures of complexes of the fifth period elements indium and antimony, and the sixth period element bismuth with the soft scorpionate ligand, hydrotris(methimazolyl)borate (Tm(Me)) are reported. A considerable variety of structural motifs were obtained by reaction of the main-group element halide and NaTm(Me). The indium(III) complexes took the form [In(kappa(3)-Tm(Me))(2)](+). This motif could not, however, be isolated for antimony(III), the dominant product being [Sb(kappa(3)-Tm(Me))(kappa(1)-Tm(Me))X] (X = Br, I). An iodo-bridged species [Sb(kappa(3)-Tm(Me))I(mu(2)-I)](2), analogous to a previously reported bismuth complex, was also isolated. Reaction of antimony(III) acetate with NaTm(Me) results in a remarkable species in which three different ligand binding modes are observed. In each antimony complex the influence of the nonbonded electron pair is observed in the structure. Bismuth halides form complexes analogous to those of antimony, with directional lone pairs, but in addition, reaction of Bi(NO(3))(3) with NaTm(Me) results in a complex with a regular S(6) coordination sphere and a nonstereochemically active lone pair. Comparisons are drawn with known Tm(Me) complexes of As, Sn, and Bi in which the stereochemical influence of the lone pairs is negligible and with Tm(Me) complexes of Te and Bi in which the lone pairs are stereochemically active. This study highlights the ability of Tm(Me) to coordinate in a variety of modes as dictated by the metal centre with no adverse effects on the stability of the complexes formed.