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Intramolecular Complex (intramolecular + complex)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Crystallization of FLINC4, an intramolecular LMO4,ldb1 complex

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2003
Janet E. Deane
LMO4 is the most recently discovered member of a small family of nuclear transcriptional regulators that are important for both normal development and disease processes. LMO4 is comprised primarily of two tandemly repeated LIM domains and interacts with the ubiquitous nuclear adaptor protein ldb1. This interaction is mediated via the LIM domains of LMO4 and the LIM-interaction domain (LID) of ldb1. An intramolecular complex, termed FLINC4, consisting of the two LIM domains from LMO4 linked to the LID domain of ldb1 via a flexible linker has been engineered, purified and crystallized. The trigonal crystals, which belong to space group P312 with unit-cell parameters a = 61.3, c = 93.2,Å, diffract to 1.3,Å resolution and contain one molecule of FLINC4 per asymmetric unit. Native and multiple-wavelength anomalous dispersion (MAD) data collected at the Zn X-ray absorption edge have been recorded to 1.3 and 1.7,Å resolution, respectively. Anomalous Patterson maps calculated with data collected at the peak wavelength show strong peaks sufficient to determine the positions of four Zn atoms per asymmetric unit. [source]

Crystallization and diffraction of an Lhx4,Isl2 complex

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 2 2009
Morgan S. Gadd
A stable intramolecular complex comprising the LIM domains of the LIM-homeodomain protein Lhx4 tethered to a peptide region of Isl2 has been engineered, purified and crystallized. The monoclinic crystals belonged to space group P21, with unit-cell parameters a = 46.8, b = 88.7, c = 49.9,Å, , = 111.9°, and diffracted to 2.16,Å resolution. [source]

Novel Probes Showing Specific Fluorescence Enhancement on Binding to a Hexahistidine Tag

CHEMISTRY - A EUROPEAN JOURNAL, Issue 26 2008
Mie Kamoto
Abstract The introduction of hexahistidine (His tag) is widely used as a tool for affinity purification of recombinant proteins, since the His tag binds selectively to nickel,nitrilotriacetic acid (Ni2+,NTA) complex. To develop efficient "turn-on" fluorescent probes for His-tagged proteins, we adopted a fluorophore displacement strategy, that is, we designed probes in which a hydroxycoumarin fluorophore is joined via a linker to a metal,NTA moiety, with which it forms a weak intramolecular complex, thereby quenching the fluorescence. In the presence of a His tag, with which the metal,NTA moiety binds strongly, the fluorophore is displaced, which results in a dramatic enhancement of fluorescence. We synthesized a series of hydroxycoumarins that were modified by various linkers with NTA (NTAC ligands), and investigated the chemical and photophysical properties of the free ligands and their metal complexes. From the viewpoint of fluorescence quenching, Ni2+ and Co2+ were the best metals. Fluorescence spectroscopy revealed a 1:1 binding stoichiometry for the Ni2+ and Co2+ complexes of NTACs in pH,7.4 aqueous buffer. As anticipated, these complexes showed weak intrinsic fluorescence, but addition of a His-tagged peptide (H-(His)6 -Tyr-NH2; Tyr was included to allow convenient concentration measurement) in pH,7.4 aqueous buffer resulted in up to a 22-fold increase in the fluorescence quantum yield. We found that the Co2+ complexes showed superior properties. No fluorescence enhancement was seen in the presence of angiotensin,I, which contains two nonadjacent histidine residues; this suggests that the probes are selective for the polyhistidine peptide. [source]

Enantioselective Recognition of Aliphatic Amino Acids by ,-Cyclodextrin Derivatives Bearing Aromatic Organoselenium Moieties on the Primary or Secondary Side

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2003
Yu Liu
Abstract Spectrophotometric titrations have been performed in order to determine the stability constants of inclusion complexation of some aliphatic amino acids with four structurally related organoselenium-modified ,-cyclodextrins: mono(6-phenylseleno-6-deoxy)-,-cyclodextrin (1a), mono[6-(p -methoxyphenylseleno)-6-deoxy]-,-cyclodextrin (1b), mono(2-phenylseleno-2-deoxy)-,-cyclodextrin (2a), and mono[2-(p -methoxyphenylseleno)-2-deoxy]-,-cyclodextrin (2b). Conformation analysis by circular dichroism and 2D NMR spectroscopic studies revealed that the aryl-substituted ,-cyclodextrins gave self-inclusion intramolecular complexes in aqueous solution, while the extent of penetration depended both on the positions and on the structures of substituents. Quantitative investigation on the binding ability of the hosts with amino acids showed that they were able to recognize the size and the shape of guests, affording supramolecular complexes with quite small stability constants ranging from 24 to 355 M,1. The molecular recognition abilities are discussed from the viewpoints of induced-fitting mechanisms, geometric complementary, and cooperative binding processes. Furthermore, these ,-cyclodextrin derivatives displayed considerable enantioselectivity towards L/D -amino acid isomers, giving the highest L -enantioselectivity (up to 8.4) for inclusion complexation between leucine and 2a. The binding modes of L/D -leucine with 1b were elucidated from NOESY studies and the chiral recognition phenomena were interpreted accordingly. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Intramolecular phenylborane complexes with monobasic bidentate Schiff bases

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 2 2007
Shweta Gaur
Abstract A series of intramolecular complexes with Schiff base ligands having N,S and N,O donor systems were synthesized in an open vessel under microwave irradiation (MWI) using a domestic microwave oven. The reaction time has been brought down from hours to seconds with improved yield as compared with the conventional heating. The complexes have been characterized on the basis of elemental analysis, conductance measurements and spectroscopic analysis. Based on the IR, 1H NMR, 11B NMR and 13C NMR spectroscopic studies, a tetrahedral geometry has been proposed for the resulting complexes. The compounds have been screened in vitro against bacteria and fungi to test their antimicrobial property and in vivo in male albino rats to test their antifertility property. The testicular sperm density, motility and density of cauda epididymal spermatozoa along with biochemical parameters of reproductive organs have been examined and discussed. Copyright © 2007 John Wiley & Sons, Ltd. [source]