Bradford protein assay

About: Bradford protein assay is a research topic. Over the lifetime, 635 publications have been published within this topic receiving 239107 citations.

Sensitive Protein Assay with Distinction of Conformations Based on Visible Absorption Changes of Citrate-Stabilized Gold Nanoparticles

Abstract: In this work, we introduce a new and potentially general method of assay of proteins in solution. In addition, the method could distinguish conformations of protein (native and denatured forms). The method is based on the changes in visible absorption spectra of citrate-stabilized Au nanoparticles (NPs) upon addition of a measured amount of protein. The behavior of four proteins, namely α-amylase, green fluorescent protein (GFP), amyloglucosidase (AMG) and bovine serum albumin (BSA) have been found to be different with respect to changes in the spectra of Au NPs. The spectral behaviors were also different between the native and denatured forms of the same protein. Interestingly, spectral changes in the presence of thiol-containing proteins (α-amylase and GFP) were different from those that either did not contain thiol at all or contained thiol that was not exposed to the solution (AMG and BSA). Transmission electron microscopic investigations revealed agglomeration of Au NPs in the presence of protein as ...

Tannic acid reduces recovery of water-soluble carbon and nitrogen from soil and affects the composition of Bradford-reactive soil protein

Abstract: Tannins are plant-derived polyphenolic compounds that precipitate proteins, bind to metals and complex with other compounds. Solutions of tannic acid, or other phenolic compounds, were added to soil samples to determine if they would affect recovery of soluble soil carbon (WSC) or –nitrogen (WSN) or influence the extraction and composition of Bradford-reactive soil protein (BRSP), associated with glomalin. Tannic acid-C added with water was not completely recovered from samples and the amount of total net WSC and WSN recovered was reduced, suggesting formation of insoluble complexes. By comparison, non-tannin phenolics like gallic acid, or methyl gallate, had little effect on extraction of WSC or WSN while a simple gallotannin derived from tannic acid, 1,2,3,4,6-penta- O -galloyl- d -glucose (PGG), inhibited extraction most. The C and N concentrations in BRSP increased when soil samples were treated with tannic acid or PGG before extraction, a procedure that includes autoclaving. Increases were greatest in the 10–20 cm compared to 0–5 cm depth. Accompanying these were declines in the ratio of absorbance at 465 and 665 nm ( E 4/ E 6 ratio) of BRSP extracts suggesting formation of larger or heavier molecules. In contrast, C and N composition in lyophilized BRSP was unaffected or even slightly reduced when tannic acid or PGG were added to the BRSP extract solution after the extraction process. We conclude that some tannins can reduce the solubility of labile soil C and N, at least temporarily and given unpredictability of response associated with phenolic substances, the Bradford assay should not be relied on to quantify pools or composition of soil proteins like glomalin.

Enhancement of Rayleigh Light Scattering of Acid Chrome Blue K by Proteins and Protein Assay by the Scattering Technique

Abstract: 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 µg 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 least 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.