RESUMO
The conformational changes of 3,5,3'-triiodo L-thyronine induced by interaction with phospholipids were analyzed by Raman spectroscopy. The spectra were interpreted in terms of two conformers of this hormone in equilibrium in the lipid medium, depending on the orientation of the 3'-iodine with respect to the ring alpha. Theoretical geometry optimizations on both conformers in vacuo and in different solvents, together with the respective calculated energies support the experimental results. The presence of only one iodine atom in the phenolic ring allows assumption of a higher flexibility of 3,5,3'-triiodo L-thyronine and a better accommodation into the lipid medium compared to 3,5,3',5'-tetraiodo L-thyronine. The possible physiological implications of structural differences that appear in membrane models between 3,5,3'-triiodo L-thyronine and 3,5,3',5'-tetraiodo L-thyronine are discussed.
Assuntos
Tri-Iodotironina/química , Animais , Gema de Ovo/química , Fosfatidilcolinas/química , Conformação Proteica , Espectrofotometria Infravermelho , Análise Espectral Raman , Tiroxina/química , Tiroxina/fisiologia , Tri-Iodotironina/fisiologiaRESUMO
The Raman spectrum of liquid N-(fluorosulfonyl)imidosulfurous difluoride FSO2N = SF2 and the IR spectrum of its vapour phase were recorded. The observed features in combination with the theoretical studies indicate the existence at room temperature of only one conformer. In accord with previous results obtained by electron-diffraction analysis, this single conformer possesses C1 symmetry in which the SF2 group is oriented syn with respect to the N-S single bond. Theoretical vibrational spectra were also determined using ab initio and density functional theory (DFT) calculations at different levels of approximation. For all except one of the torsional modes, experimental wavenumbers were obtained. A subsequent normal coordinate analysis was performed using a torsional wavenumber calculated by theoretical methods.
Assuntos
Fluoretos/química , Elétrons , Modelos Moleculares , Nitrogênio/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Análise Espectral Raman/métodos , Enxofre/química , TemperaturaRESUMO
We established two immortalized cell lines from cerebral cortex of normal (CNh) and trisomy 16 (CTb) mouse fetuses, an animal model of human trisomy 21. Those cells loaded with the fluorescent Ca2+ dyes, Indo-1 and Fluo-3, exhibited increments of intracellular Ca2+ ([Ca2+]i) in response to external glutamate, NMDA, AMPA and kainate. CTb cells exhibited higher basal Ca2+ concentrations and had higher amplitude and slower time-dependent kinetics in the decay than CNh cells, suggesting an impaired Ca2+ buffering capacity in the trisomy 16-derived cell line. Nicotine also induced increments of [Ca2+]i. The CTb cell line could represent a model for studying cellular alterations related to Down syndrome.
Assuntos
Sinalização do Cálcio/fisiologia , Córtex Cerebral/fisiologia , Cromossomos Humanos Par 16 , Trissomia , Animais , Cálcio/metabolismo , Linhagem Celular Transformada , Córtex Cerebral/citologia , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/embriologia , Feto/citologia , Ácido Glutâmico/farmacologia , Humanos , Membranas Intracelulares/metabolismo , Ácido Caínico/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Nicotina/farmacologia , Concentração Osmolar , Receptores de Glutamato/metabolismo , Valores de Referência , Trissomia/genética , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/farmacologiaRESUMO
Microbial lipids produced byRhodotorula glutinis grown in continuous culture with molasses under nitrogen-limiting conditions were evaluated and the effects of growth rate on fatty acid composition were studied. As the growth rate decreased, cell biomass, lipid content and lipid yield gradually increased. The maximum lipid content recorded was 39% (w/w) of dry cell biomass at a dilution rate of 0.04 h(-1). The growth rate also affected fatty acid composition: oleic acid decreased with decreasing growth rate while stearic acid increased.