Search results for "dimer"

Quantitative characterization of tetraspanin 8 homointeractions in the plasma membrane

2021

The spatial distribution of proteins in cell membranes is crucial for signal transduction, cell communication and membrane trafficking. Members of the Tetraspanin family organize functional protein clusters within the plasma membrane into so-called Tetraspanin-enriched microdomains (TEMs). Direct interactions between Tetraspanins are believed to be important for this organization. However, studies thus far have utilized mainly co-immunoprecipitation methods that cannot distinguish between direct and indirect, through common partners, interactions. Here we study Tetraspanin 8 homointeractions in living cells via quantitative fluorescence microscopy. We demonstrate that Tetraspanin 8 exists i…

Comprehensive analysis of expression, subcellular localization, and cognate pairing of SNARE proteins in oligodendrocytes

2009

Oligodendrocytes form the central nervous system myelin sheath by spiral wrapping of their plasma membrane around axons, necessitating a high rate of exocytic membrane addition to the growing myelin membrane. Membrane fusion is mediated by soluble N-ethylmaleimide-sensitive factor attachment protein receptor proteins (SNAREs), which act by specific pairing of vesicle (R)- and target (Q)-SNAREs. To characterize oligodendroglial SNAREs and their trafficking pathways, we performed a detailed expression analysis of SNAREs in differentiating cultured oligodendrocytes and myelin and determined their subcellular localization. Expression of the plasma membrane Q-SNAREs syntaxin 3, syntaxin 4, SNAP2…

Cissampeloflavone, a chalcone-flavone dimer from Cissampelos pareira

2003

From the aerial parts of Cissampelos pareira L. (Menispermaceae), a chalcone-flavone dimer has been isolated which, mainly from NMR spectroscopic and MS data, was proved to be 2-(4-hydroxy-3-methoxyphenyl)-7-(4-methoxyphenyl)-6-(2-hydroxy-4,6-dimethoxybenzoyl)-furano[3,2-g]benzopyran-4-one. This has been assigned the trivial name cissampeloflavone. The compound has good activity against Trypanosoma cruzi and T. brucei rhodesiense and has a low toxicity to the human KB cell line.

Erratum to “Cissampeloflavone, a chalcone–flavone dimer from Cissampelos pareira”[Phytochemistry 64 (2003) 645–647]

2003

Biochemical analysis of class II antigens. Identification of a two- and a three-polypeptide chain complex of I-A locus equivalent molecules in the ra…

1983

The polypeptide chain composition of class II antigens from LEW rat spleen cells was studied utilizing cross-reactive mouse alloantiserum A. TH anti-A.TL (specificity anti-Iak) and the monoclonal antibodies MRC-OX6 and MRC-OX3 for immunoprecipitation. Two-dimensional gel mapping of A. TH anti-A. TL immunoprecipitates revealed that, as in the mouse, two groups of class II antigens exist corresponding to I-A and I-E locus equivalent structures. In the absence of reducing agents three monomeric chains α, 36 kDa (p36); γ, 33 kDa (p33); and β, 23 kDa (p23), were detected for I-A equivalent antigens, whereas I-E equivalent molecules separated into five monomeric chains: α, 37 kDa (p37); γ, 33 kDa…

Die thermische polymerisation von methylmethacrylat, 2. Bildung des ungesättigten dimeren

1980

The spontaneous thermal polymerization of methyl methacrylate (MMA) is accompanied by the production of serveral oligomers among which a linear unsaturated dimer H-1 (dimethyl 1-hexene-2,5-dicarboxylate) is predominant. The reaction kinetics of this dimer formation was investigated in bulk and in solution. The temperature dependence of the second order dimerization constant was determined as Reaction mechanisms for the thermal dimer formation of MMA are discussed.

On the electronic structure of a dianion, a radical anion, and a neutral biradical (HB)11CCCC(BH)11 carborane dimer

2009

Abstract The electronic structure of a neutral, a radical anion, and a dianion carborane dimer connected via an acetylenic bridge unit (HB) 11 C C C C(BH) 11 is analyzed by quantum chemical methods. Geometries, relative stabilities, and singlet–triplet gaps are determined in the neutral and dianion species for the lowest-lying singlet and triplet states and for the doublet ground state in the radical anion. As for the recently studied biradical compounds derived from o -carborane, m -carborane and p -carborane [J. Chem. Theory Comput. 4 (2008) 1338] via double hydrogen abstraction, the neutral dimeric compound displays a biradical ground-state structure in which both singlet and triplet sta…

The Triplet Excimer of Naphthalene: A Model System for Triplet−Triplet Interactions and Its Spectral Properties

2011

Basic concepts of triplet excimer formation and triplet−triplet interactions between molecules with conjugated π-systems are investigated by means of ab initio quantum chemical calculations, employing the second-order coupled-cluster method CC2 and the second-order propagator method ADC(2). The naphthalene dimer turns out to be a very fruitful model system for which weak and strong electronic coupling can be identified depending on the mutual arrangement of the monomer moieties. From geometry optimizations in the excited state, we determine binding energies, including solvent effects, and transient absorption spectra. The most stable T1 conformation turns out to be a face-to-face arrangemen…

2-[(1-Methyl-1H-pyrrol-2-yl)carbonyl-meth-yl]isoindoline-1,3-dione.

2009

The asymmetric unit of the title compound, C15H12N2O3, contains two almost identical molecules forming an nearly C2-symmetric dimeric pattern. The dihedral angles between the pyrrole ring and the phthalimide unit are 82.95 (8) and 86.57 (8)° for the two molecules. Within such a dimer, the phthalimide units of the two molecules form a dihedral angle of 1.5 (5)°.

Thermal behaviour and electrochemical properties of bis(trifluoromethanesulfonyl)amide and dodecatungstosilicate viologen dimers

2012

We report the synthesis and characterization of dimeric viologen salts (1',1''-(alkane-1,n-diyl)bis(1-ethyl-4,4'-bipyridinium) with n = 4-10) with bis(trifluoromethanesulfonyl)amide (bistriflimide, Tf(2)N(-)) as a counteranion. For n = 4, 5 and 6, and for the nonylviologen cation (1,1'-dinonyl-4,4'-bipyridinium) we also prepared salts with the totally inorganic dodecatungstosilicate anion, SiW(12)O(40)(4-), featuring a poly-charged surface and nanosized dimensions. The materials have been characterized by means of calorimetric techniques, X-ray diffraction and solid state NMR and a comparison is made with analogous monomeric viologen salts exhibiting smectic mesophases. A strong odd-even ef…