Chun Qi Ma

Microdetermination of proteins by Rayleigh light scattering technique with acid green 25

Abstract Based on the enhancement of Rayleigh light scattering (RLS) of acid green 25 (Ag25) by proteins, a new quantitative determination method for proteins in aqueous solutions has been developed. This assay is very sensitive (0.136-10.20 μg/ml), rapid (

Determination of proteins by fluorescence quenching of erythrosin B

Abstract Erythrosin B (EB) binding to proteins causes a decrease in the fluorescence maximum of EB at 550 nm. Based on this, a new, fast and simple fluorescence quenching method for the determination of proteins is developed. The linear range of this assay is 1.36–20.4 μg ml −1 . The method has very few interferences, most of which can be minimized by dilution. In the detection of proteins in human serum, this method gave values close to that of the Coomassie brilliant blue method.

Enhancement of Rayleigh light scattering of acid chrome blue K by proteins and protein assay by the scattering technique.

Rayleigh light scattering of Acid Chrome Blue K (ACBK) is enhanced greatly by proteins. Based on this, a method for protein assay in aqueous solution was developed. This assay matches the sensitivity of the colorimetric dye-binding method with a linear range of 0.136-10.88 micrograms ml-1. The measurements can be made easily on a common fluorimeter. The reaction between ACBK and proteins is completed in 2 min and the scattered light signal is stable for at lest 3 h. Protein-to-protein variability is encountered in this method as in many other protein assays. There is little or no interference from amino acids, most metal ions and complexing agents (e.g., EDTA). Interferences from salts, urea and detergents can be minimized by dilution.

Spectrophotometric micromethod for protein determination with tetrachloro tetraiodo fluorescein

Abstract Reaction of tetrachloro tetraiodo fluorescein (Na2TCTIF) with protein results in an increase in its absorption at 568nm. This assay gives a linear response to BSA at 0.68–34.0 μg /ml, and is almost as sensitive as the Bradford method1. The reaction is completed in approximately 2 min and has good color stability for at least 1 h. Addition of triton X-100 increases the sensitivity and stability of Na2TCTIF binary system and the reason was studied. The binary and ternary assays were compared in protein-to-protein variability, interferences and the type of binding effort. In detection of human serum albumin, these two ways give results with good reproducibility and are comparable with the bromocresol green (BCG) method.