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Different Charge (different + charge)

Distribution by Scientific Domains
Chemistry50%

Terms modified by Different Charge

  • different charge states
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    Selected Abstracts

    Effect of fatty acid-binding proteins on intermembrane fatty acid transport

    FEBS JOURNAL, Issue 19 2000
    Studies on different types, mutant proteins
    Liposomes of different charge fixed to nitrocellulose filters were used to study the transfer of fatty acids to rat heart or liver mitochondria in the presence of fatty acid-binding protein (FABP) or albumin. [14C]Palmitate oxidation was used as a parameter. Different FABP types and heart FABP mutants were tested. The charge of the liposomes did not influence the solubilization and mitochondrial oxidation of palmitate without FABP and the amount of solubilized palmitate in the presence of FABP. Mitochondria did not show a preference for oxidation of FABP-bound palmitate over their tissue-specific FABP type. All FABP types increased palmitate oxidation by heart and liver mitochondria with neutral, positive and negative liposomes by 2.5-fold, 3.2-fold and twofold, respectively. Ileal lipid-binding protein and H-FABP mutants that do not bind fatty acid had no effect. Other H-FABP mutants had different effects, dependent on the site of mutation. The effect of albumin was similar to, but not dependent on, liposome charge. The ionic strength had only a slight effect. In conclusion, the transfer of palmitate from liposomal membranes to mitochondria was increased by all FABP types to a similar extent. The membrane charge had a large effect in contrast to the origin of the mitochondria. [source]

    Ab Initio Quantum Chemical Investigation of the First Steps of the Photocycle of Phototropin: A Model Study,

    PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2003
    Christian Neiß
    ABSTRACT Phototropin is a blue light,activated photoreceptor that plays a dominant role in the phototropism of plants. The protein contains two subunits that bind flavin mononucleotide (FMN), which are responsible for the initial steps of the light-induced reaction. It has been proposed that the photoexcited flavin molecule adds a cysteine residue of the protein backbone, thus activating autophosphorylation of the enzyme. In this study, the electronic properties of several FMN-related compounds in different charge and spin states are characterized by means of ab initio quantum mechanical calculations. The model compounds serve as idealized model chromophores for phototropism. Reaction energies are estimated for simple model reactions, roughly representing the addition of a cysteine residue to the flavin molecule. Excitation energies were calculated with the help of time-dependent density functional theory. On the basis of these calculations we propose the following mechanism for the addition reaction: (1) after photoexcitation of FMN out of the singlet ground state S0, excited singlet state(s) are populated; these relax to the lowest excited singlet state S1, and subsequently by intersystem crossing FMN in the lowest triplet state, T1 is formed; (2) the triplet easily removes the neutral hydrogen atom from the H,S group of the cysteine residue; and (3) the resulting thio radical is added. [source]

    Heparin release from slippery-when-wet guide wires for intravascular use

    JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 6 2002
    Camiel C. L. Peerlings
    Abstract Thin metallic wires with an adherent hydrophilic/ lubricious polymeric coating were manufactured in a new extrusion-like procedure. This procedure is part of a novel and efficient way of assembling lubricious guide wires for intravascular interventions, such as percutaneous transluminal angioplasty. It is reported that heparin can readily be incorporated in the hydrophilic coating. A set of heparin-containing guidewire models was made and studied in detail. This showed that (i) immersion of the guide-wire models in an aqueous environment leads to release of heparin from their surface; (ii) the presence of heparin in the coating does not impede the lubricity of the coils; (iii) addition of stearic acid in the coating, next to heparin, does not influence the lubricity of the guide-wire models. Two different charges of heparin (designated heparin-low and heparin-high) were incorporated in the coating. It is discussed that release of heparin from the surface of medical devices (e.g. guide wires and catheters) is much more effective than systemic heparinization, basically because dissolved heparin molecules have a much larger probability of simply passing a medical device's surface (axial convection) rather than contacting it (radial diffusion). © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 692,698, 2002 [source]

    Toward direct determination of conformations of protein building units from multidimensional NMR experiments VI.

    JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 13 2005
    Chemical shift analysis of his to gain 3D structure, protonation state information
    Abstract NMR,chemical shift structure correlations were investigated by using GIAO-RB3LYP/6-311++G(2d,2p) formalism. Geometries and chemical shifts (CSI values) of 103 different conformers of N,-formyl-L-histidinamide were determined including both neutral and charged protonation forms. Correlations between amino acid torsional angle values and chemical shifts were investigated for the first time for an aromatic and polar amino acid residue whose side chain may carry different charges. Linear correlation coefficients of a significant level were determined between chemical shifts and dihedral angles for CSI[1H,]/,, CSI[13C,]/,, and CSI[13C,]/,. Protonation of the imidazole ring induces the upfield shift of CSI[13C,] for positively charged histidines and an opposite effect for the negative residue. We investigated the correspondence of theoretical and experimental 13C,, 13C,, and 1H, chemical shifts and the nine basic conformational building units characteristic for proteins. These three chemical shift values allow the identification of conformational building units at 80% accuracy. These results enable the prediction of additional regular secondary structural elements (e.g., polyProlineII, inverse ,-turns) and loops beyond the assignment of chemical shifts to ,-helices and ,-pleated sheets. Moreover, the location of the His residue can be further specified in a ,-sheet. It is possible to determine whether the appropriate residue is located at the middle or in a first/last ,-strand within a ,-sheet based on calculated CSI values. Thus, the attractive idea of establishing local residue specific backbone folding parameters in peptides and proteins by employing chemical shift information (e.g., 1H, and 13C,) obtained from selected heteronuclear correlation NMR experiments (e.g., 2D-HSQC) is reinforced. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1307,1317, 2005 [source]