RESUMO
Petroleum, as the major energy source, is indispensable from our lives. Presence of compounds resistant to degradation can pose risks for human health and environment. Basidiomycetes have been considered as powerful candidates in biodegradation of petroleum compounds via secreting ligninolytic enzymes. In this study a wood-decaying fungus was isolated by significant degradation ability that was identified as Daedaleopsis sp. by morphological and molecular identification methods. According to GC/MS studies, incubation of heavy crude oil with Daedaleopsis sp. resulted in increased amounts of
Assuntos
Basidiomycota/fisiologia , Biodegradação Ambiental , Petróleo/metabolismo , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Basidiomycota/classificação , Basidiomycota/isolamento & purificação , DNA Espaçador Ribossômico , Cromatografia Gasosa-Espectrometria de Massas , Concentração de Íons de Hidrogênio , Filogenia , TemperaturaRESUMO
Ion pair of cationic surfactant (cetytrimethylammonium bromide) and tungestosilicic acid incorporated in PVC matrix, was used for coating a piece of copper wire as a new high sensitive SPME fiber in extraction and determination of BTEX compounds from the headspace of water samples prior to GC/FID analysis. Under optimum extraction conditions, limits of detection for benzene, toluene, ethylbenzene, p-xylene, m-xylene and o-xylene were found to be 1.18, 5.61, 0.87, 0.29, 0.22 and 0.33 ng L(-1) respectively. Low detection limits, wide linear dynamic ranges, good reproducibility (RSD% 1.48-4.27), high fiber capacity and high mechanical durability are some of the most important advantages of the new fiber.
Assuntos
Derivados de Benzeno/análise , Benzeno/análise , Tensoativos/química , Tolueno/análise , Xilenos/análise , Cátions , Nanotecnologia , Microextração em Fase SólidaRESUMO
In this study camel alphaS(1)-casein (alphaS(1)-CN) was purified, using a two-step purification procedure. The anti-aggregation (chaperone-like) ability of the purified protein sample was examined in a wide range of experimental conditions and at different concentrations of camel alphaS(1)-CN, in the presence of salts and sodium dodecyl sulfate (SDS). To examine chaperone-like activity of camel alphaS(1)-CN, bovine pancreatic insulin was used as the target protein. Insulin aggregation performed chemically in the presence of 20 mM dithiotreitol (DTT) and was studied at 360 nm wavelength by UV-vis spectrophotometer. Camel alphaS(1)-CN exhibited a dose-dependent chaperone-like activity as the molar ratios of chaperone/target protein varied between 0 and 0.07. The presence of salts or surfactants changing the protein properties had an influence on chaperone capacity of camel alphaS(1)-CN. The results of UV-visible and fluorimetric measurements indicated that the salts neutralize the chaperone-like activity of casein due to dehydration effect and the increased association and aggregation of proteins, while SDS plays a role as chaperone and chaperone-like properties of camel alphaS(1)-CN enhanced in the presence of SDS due to the binding of the hydrophobic tail of SDS and alphaS(1)-CN to the exposed hydrophobic sites of insulin strongly preventing aggregation of insulin.
Assuntos
Camelus/metabolismo , Caseínas/metabolismo , Insulina/metabolismo , Chaperonas Moleculares/metabolismo , Sais/farmacologia , Dodecilsulfato de Sódio/farmacologia , Naftalenossulfonato de Anilina/metabolismo , Animais , Bovinos , Ditiotreitol/farmacologia , Fluorescência , Interações Hidrofóbicas e Hidrofílicas , Insulina/química , Estrutura Quaternária de ProteínaRESUMO
Sodium dodecyl sulfate (SDS) at low concentrations considerably enhanced insulin aggregation and reduced the chaperone-like activity of purified camel alphaS(1)-casein (alphaS(1)-CN). These observed changes were the result of repulsive electrostatic interactions between both negative charged head groups of SDS and alphaS(1)-CN, and the net negative charge of insulin molecules, resulting in the greater exposure of hydrophobic patches of insulin and its enhanced aggregation. In contrast, enhanced hydrophobic interactions were primarily responsible for the conformational changes observed in insulin and alphaS(1)-CN at high SDS concentrations, resulting in increased binding of SDS and alphaS(1)-CN to insulin and its reduced aggregation.