Photochemical Behavior of Lysozyme-4-(2-pyridylazo)-resorcinol Polymolecular Complex and Its Analytical Applications

Fluorescent labeling of proteins with amine-specific 1,3,2-(2H)-dioxaborine polymethine dye

A novel water-soluble amine-reactive dioxaborine trimethine dye was synthesized in a good yield and characterized. The potential of the dye as a specific reagent for protein labeling was demonstrated with bovine serum albumin and lysozyme. Its interaction with proteins was studied by fluorescence spectroscopy and gel electrophoresis. The covalent binding of this almost nonfluorescent dye to proteins results in a 75- to 78-fold increase of its emission intensity accompanied by a red shift of the fluorescence emission maximum by 27 to 45 nm, with fluorescence wavelengths of labeled biomolecules being more than 600 nm. The dye does not require activation for the labeling reaction and can be used in a variety of bioassay applications.

Rapid and sensitive determination of trace chloride ion in drinks using resonance light scattering technique

A resonance light scattering (RLS) technique to determine chloride ions in drinks was developed. Chloride ions were found to bind Ag(+) forming AgCl aggregates that produced intense resonance scattering light. Effects of factors such as acidity, ionic strength, and coexistent interferents on the RLS of AgCl aggregates were investigated. The pH of solution almost did not affect the production of RLS and few foreign species interfered with the detection of chloride ions. The resonance scattering light intensity at the maximum peak of 571 nm was linear to the concentration of chloride ions in the range of 1.42-8.52 ng mL(-1) with a detection limit of 0.71 ng mL(-1). To determine the feasibility of the proposed method, some samples of water and drinks were analyzed. The attained results were in agreement with that of ion-selective electrode method. Good recovery results were also obtained with the range of 94.08-105.63%. The sensitivity and selectivity of the RLS method are high enough to determine trace amounts of chloride ions without any significant interference from high concentration of other components such as common anions and cations.

Study on the Interaction Mechanism of Lysozyme and Bromophenol Blue by Fluorescence Spectroscopy

The interaction of lysozyme with bromophenol blue (BPB) in acetate buffer (pH 6.0) was studied by fluorescence quenching method for the first time. It was found that BPB could conspicuously quench the fluorescence of lysozyme by the static quenching process, possibly due to the binding on the active site near Trp62. The binding parameters including the binding constant and the number of binding site were calculated. The thermodynamic parameters DeltaH degrees, DeltaS degrees and DeltaG degrees at different temperatures were obtained. The formation of lysozyme-BPB complex depended on the cooperation of the hydrophobic and electrostatic forces. And the binding average distance between lysozyme and BPB was determined. The effect of common metal ions on the binding constant of lysozyme-BPB was also examined.