RESUMEN
The interaction between ribavirin (RIB) with bovine serum albumin (BSA) has been investigated by fluorescence quenching technique in combination with UV-vis absorption and circular dichroism (CD) spectroscopies under the simulative physiological conditions. The quenching of BSA fluorescence by RIB was found to be a result of the formation of RIB-BSA complex. The binding constants and the number of binding sites were calculated at three different temperatures. The values of thermodynamic parameters ∆H, ∆S, ∆G at different temperatures indicate that hydrophobic and hydrogen bonds played important roles for RIB-BSA association. The binding distance r was obtained according to the theory of Förster's non-radiation energy transfer. The displacement experiments was performed for identifying the location of the binding site of RIB on BSA. The effects of common ions on the binding constant of RIB and BSA were also examined. Finally, the conformational changes of BSA in the presence of RIB were also analyzed by CD spectra and Synchronous fluorescence spectra.
Asunto(s)
Ribavirina/metabolismo , Albúmina Sérica Bovina/metabolismo , Análisis Espectral/métodos , Animales , Sitios de Unión , Bovinos , Dicroismo Circular , Transferencia de Energía , Iones , Cinética , Ribavirina/química , Espectrometría de Fluorescencia , TemperaturaRESUMEN
The fluorescence spectra of protoporphyrin IX (PPIX) solutions and human serum samples were measured and analyzed under physiological conditions. The experimental results showed that the fluorescence of PPIX in human serum was mainly derived from PPIX-serum albumin complex. Moreover, the effects of serum albumin and PPIX on the PPIX emission fluorescence were also investigated. Compared with pure PPIX solution, not only a red-shift of PPIX fluorescence peak was found for PPIX+albumin solution, but also albumin had a fluorescence enhancement effect on protoporphyrin IX. For the mixture of PPIX+albumin, with the increase of PPIX the wavelength of the PPIX emission peak will increased a little when its concentration was less than 0.8 x 10(-5) mol x L(-1), but was nearly invariable when its concentration was more than 0.8 x 10(-5) mol x L(-1).
Asunto(s)
Protoporfirinas/sangre , Espectrometría de Fluorescencia/métodos , Animales , Bovinos , Humanos , Protoporfirinas/química , Albúmina Sérica Bovina/químicaRESUMEN
A method was developed for the determination of As, Pb, Sn, Sb and Bi in high temperature iron and nickel-based alloy by graphite furnace atomic absorption spectrometry combined with liquid-liquid extraction. These elements formed complexes with I- ions and were subsequently extracted into MIBK to be separated from matrix elements. The effects of remnant matrix elements were studied in detail. Meanwhile, the interferences of other elements, such as W, Nb and Ta, were eliminated with masking method. The recovery rates for As, Pb, Sn, Sb and Bi are in the range of 93%-99%, and the relative standard deviations are from 8.8% to 12%.
RESUMEN
Determination of trace element arsenic in high purity nickel by GFAAS in STPF conditions is described in this paper. The dry time, ashing temperature and atomization temperature are obtained by optimization process. The standard solutions are matched to eliminate the influences of matrix nickel, and nickel is also as the chemical matrix modifier in the detected. The characteristic mass of the method is 1.9 pg, the average relative standard deviation is 1.4%, the recovery rate is in the range of 95%-103%.