RESUMO
Changes in the conformation of apoliprotein B-100 in the early stages of copper-mediated low density lipoprotein oxidation have been monitored by infrared spectroscopy. During the lag phase no variation in structure is observed, indicating that copper binding to the protein does not significantly affect its structure. In the propagation phase, while hydroperoxides are formed but the protein is not modified, no changes in secondary structure are observed, but the thermal profile of the band corresponding to alpha-helix is displaced in frequency, indicating changes in tertiary structure associated with this conformation but not with beta-sheet components. When aldehyde formation starts, a decrease of approximately 3% in the area of bands corresponding to alpha-helix and beta-sheet is produced, concomitantly with an increase in beta-turns and unordered structure. The two bands corresponding to beta-turns vary as well under these conditions, indicating changes in these structures. Also at this stage the thermal profile shows variations in frequency for the bands corresponding to both alpha-helix and beta-sheet. The results are consistent with the hypothesis that as soon as the polyunsaturated fatty acids from the particle core are modified, this change is reflected at the surface, in the alpha-helical components contacting the monolayer.
Assuntos
Apolipoproteínas B/química , Lipoproteínas LDL/química , Apolipoproteínas B/metabolismo , Cobre/química , Cobre/metabolismo , Humanos , Lipoproteínas LDL/metabolismo , Oxirredução , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Espectrofotometria Infravermelho , TemperaturaRESUMO
The ability of astaxanthin and canthaxanthin as chain-breaking antioxidants was studied in Cu(2+)-initiated peroxidation of phosphatidylcholine large unilamellar vesicles (LUVs). Both carotenoids increased the lag period that precedes the maximum rate of lipid peroxidation, though astaxanthin showed stronger activity. For these experiments, different amounts of xanthophylls were exogenously added to previously made LUVs, non-incorporated pigment being afterwards removed. Differential scanning calorimetry assays with L-beta,gamma-dimyristoyl-alpha-phosphatidylcholine LUVs demonstrated that xanthophylls incorporated as described interact with the lipid matrix becoming interspersed among the phospholipid molecules.
Assuntos
Antioxidantes/química , Antioxidantes/farmacologia , Carotenoides/química , Carotenoides/farmacologia , Peroxidação de Lipídeos/efeitos dos fármacos , Lipossomos/química , Varredura Diferencial de Calorimetria , Cantaxantina/química , Cantaxantina/farmacologia , Dimiristoilfosfatidilcolina/química , Técnicas In Vitro , Xantofilas , beta Caroteno/análogos & derivados , beta Caroteno/química , beta Caroteno/farmacologiaRESUMO
"The larval gonad of Bufo arenarum exposed to thyroid hormone" In order to analyze the effect of thyroid hormone on the Bufo arenarum's gonad, that is a "undifferentiated race", the embryos were exposed to tri-iodo-thyronine. The results suggest that in this species, gonadal differentiation would be related to thyroid hormone. Moreover, we can observe that the number of oocytes are increased and that they are more ripe than in the control gonads.
Assuntos
Gônadas/embriologia , Diferenciação Sexual/efeitos dos fármacos , Tri-Iodotironina/farmacologia , Animais , Bufo arenarum , Gônadas/patologia , Metamorfose Biológica/efeitos dos fármacos , Tri-Iodotironina/administração & dosagemRESUMO
[quot ]The larval gonad of Bufo arenarum exposed to thyroid hormone[quot ] In order to analyze the effect of thyroid hormone on the Bufo arenarums gonad, that is a [quot ]undifferentiated race[quot ], the embryos were exposed to tri-iodo-thyronine. The results suggest that in this species, gonadal differentiation would be related to thyroid hormone. Moreover, we can observe that the number of oocytes are increased and that they are more ripe than in the control gonads.
