Search results for "sulfide"
showing 10 items of 388 documents
Mutational analysis of disulfide bonds in the trypsin-reactive subdomain of a Bowman-Birk-type inhibitor of trypsin and chymotrypsin--cooperative ver…
1998
It is widely believed that protein folding is a hierarchical process proceeding from secondary structure via subdomains and domains towards the complete tertiary structure. Accordingly, protein subdomains should behave as independent folding units. However, this prediction would underestimate the well-established structural significance of tertiary context and domain interfaces in proteins. The principal objective of this work was to distinguish between autonomous and cooperative refolding of protein subdomains by means of mutational analysis. The double-headed Bowman-Birk inhibitor of trypsin and chymotrypsin of known crystal structure was selected for study. The relative orientation of th…
cDNA Cloning and Functional Expression of Jerdostatin, a Novel RTS-disintegrin from Trimeresurus jerdonii and a Specific Antagonist of the α1β1 Integ…
2005
Jerdostatin represents a novel RTS-containing short disintegrin cloned by reverse transcriptase-PCR from the venom gland mRNA of the Chinese Jerdons pit viper Trimeresurus jerdonii. The jerdostatins precursor cDNA contained a 333-bp open reading frame encoding a signal peptide, a pre-peptide, and a 43-amino acid disintegrin domain, whose amino acid sequence displayed 80% identity with that of the KTS-disintegrins obtustatin and viperistatin. The jerdostatin cDNA structure represents the first complete open reading frame of a short disintegrin and points to the emergence of jerdostatin from a short-coding gene. The different residues between jerdostatin and obtustatin/viperistatin are segreg…
The redox state of the cell regulates the ligand binding affinity of human neuroglobin and cytoglobin.
2003
Neuroglobin and cytoglobin reversibly bind oxygen in competition with the distal histidine, and the observed oxygen affinity therefore depends on the properties of both ligands. In the absence of an external ligand, the iron atom of these globins is hexacoordinated. There are three cysteine residues in human neuroglobin; those at positions CD7 and D5 are sufficiently close to form an internal disulfide bond. Both cysteine residues in cytoglobin, although localized in other positions than in human neuroglobin, may form a disulfide bond as well. The existence and position of these disulfide bonds was demonstrated by mass spectrometry and thiol accessibility studies. Mutation of the cysteines …
Controlling quaternary structure assembly: subunit interface engineering and crystal structure of dual chain avidin.
2006
Dual chain avidin (dcAvd) is an engineered avidin form, in which two circularly permuted chicken avidin monomers are fused into one polypeptide chain. DcAvd can theoretically form two different pseudotetrameric quaternary assemblies because of symmetry at the monomer-monomer interfaces. Here, our aim was to control the assembly of the quaternary structure of dcAvd. We introduced the mutation I117C into one of the circularly permuted domains of dcAvd and scanned residues along the 1-3 subunit interface of the other domain. Interestingly, V115H resulted in a single, disulfide locked quaternary assembly of dcAvd, whereas I117H could not guide the oligomerisation process even though it stabilis…
Two Novel Ternary Dicopper(II) μ-Guanazole Complexes with Aromatic Amines Strongly Activated by Quantum Dots for DNA Cleavage
2013
Two novel (μ-guanazole)-bridged binuclear copper(II) complexes with 1,10-phenanthroline (phen) or 2,2'-bipyridine (bipy), [Cu2(μ-N2,N4-Hdatrz)(phen)2(H2O)(NO3)4] (1) and [Cu2(μ-N1,N2-datrz)2(μ-OH2)(bipy)2](ClO4)2 (2) (Hdatrz = 3,5-diamino-1,2,4-triazole = guanazole), have been prepared and characterized by X-ray diffraction, spectroscopy, and susceptibility measurements. Compounds 1 and 2 differ in the aromatic amine, which acts as a coligand, and in the Cu···Cu'-bridging system. Compound 1, which contains two mono-bridged copper ions, represents the first example of a discrete Cu-(NCN-trz)-Cu' complex. Compound 2, with two triply bridged copper ions, is one of the few compounds featuring a…
The refined structure of functional unit h of keyhole limpet hemocyanin (KLH1-h) reveals disulfide bridges
2011
Hemocyanins are multimeric oxygen-transport proteins in the hemolymph of many arthropods and mollusks. The overall molecular architecture of arthropod and molluscan hemocyanin is very different, although they possess a similar binuclear type 3 copper center to bind oxygen in a side-on conformation. Gastropod hemocyanin is a 35 nm cylindrical didecamer (2 × 10-mer) based on a 400 kDa subunit. The latter is subdivided into eight paralogous “functional units” (FU-a to FU-h), each with an active site. FU-a to FU-f contribute to the cylinder wall, whereas FU-g and FU-h form the internal collar complex. Atomic structures of FU-e and FU-g, and a 9 A cryoEM structure of the 8 MDa didecamer are avai…
One-pot synthesis of PbS NP/sulfur-oleylamine copolymer nanocomposites via the copolymerization of elemental sulfur with oleylamine
2014
A novel synthetic and processing strategy for converting elemental sulfur into polymeric and nanocomposite materials is reported. We describe a facile one-pot reaction using elemental sulfur and oleylamine as comonomers to prepare high sulfur content copolymers and lead sulfide nanoparticle (PbS NP) nanocomposites. This process enables the preparation of solution processable copolymers and nanocomposites, where the loading and dispersion of PbS NP inclusions could be precisely controlled. We demonstrate the dual roles of oleylamine with sulfur for both the copolymerization of sulfur copolymers as well as the in situ synthesis of PbS NPs in a one-pot fashion.
Highly siderophile elements (Re, Os, Ir, Ru, Rh, Pd, Au) in impact melts from three European impact craters (Sääksjärvi, Mien, and Dellen): Clues to …
1997
Twenty-two large (10 g) impact melt samples from three Scandinavian craters (i.e., Saaksjarvi, Finland; and Mien and Dellen, Sweden) were analyzed for highly siderophile elements (HSE: platinum group elements, Rh, and Au) by the nickel sulfide technique in combination with neutron activation. The ten impact melt samples from Saaksjarvi are enriched in Ir and other highly siderophile elements (Ir = 2.48 ± 0.73 ng/g) relative to average upper crust concentrations (0.03 ± 0.02 ng/g Ir). The twelve Dellen and Mien samples are marginally enriched in Ir (0.48 ± 0.23 ng/g for Dellen, and 0.37 ± 0.23 ng/g for Mien). The amount of meteoritic component corresponds to 0.5% of a nominal CI component fo…
Clues to the nature of the impacting bodies from platinum-group elements (rhenium and gold) in borehole samples from the Clearwater East crater (Cana…
1997
— Seven large (10 g) impact melt rock samples from boreholes from the Boltysh impact crater (Ukraine) and six samples from the East Clearwater crater (Canada) were analyzed for Os, Ir, Ru, Rh, Pd, Re and Au by the nickel sulfide technique in combination with neutron activation. Earlier analyses of Clearwater East impact melt rocks have shown that they are strongly enriched in Ir, Os, Pd and Re. In this work, I confirm earlier findings and demonstrate similarly high enrichments of Rh and Ru. The average Os/Ir, Ru/Ir, Pd/Ir, Rh/Ir and Ru/Rh ratios of the melt rock samples from Clearwater East are CI-chondritic and yield an average Ir content of 25.2 ± 6.5 ng/g relative to an average upper cru…
Synthesis, NMR spectral and single crystal X-ray structural studies on Ni(II) dithiocarbamates. Fabrication of nickel sulfide nanospheres by the solv…
2014
Abstract Three dithiocarbamatonickel(II) complexes, [Ni(bzbudtc)2] (1), [Ni(bzbudtc)(PPh3)(NCS)] (2) and [Ni(bzbudtc)(PPh3)(CN)] (3) (where, bzbudtc = the N-benzyl-N-butyldithiocarbamato anion and PPh3 = triphenylphosphine), were prepared. All three complexes were analyzed by UV–Vis, IR and NMR (1H, 13C and 31P) spectra. The 13C NMR spectra of complexes 1–3 show the most crucial thioureide signal at around 200 ppm. A significant deshielding observed for the 31P signals in 2 and 3 reveals the effective bonding of phosphorus to the metal center. Single crystal X-ray analysis of crystals of 1–3 show that all the described complexes exhibit a distorted square planar coordination geometry in the…