We describe a microwave-assisted, methanol and acetic acid-free, inexpensive method for rapid staining of SDS-PAGE proteins. Only citric acid, benzoic acid, and Coomassie brilliant blue G-250 (CBG) were used. Microwave irradiation reduced the detection duration, and proteins in a clear background were visualized within 30 min of destaining, after 2 min of fixing and 12 min of staining. By using this protocol, comparable band intensities were obtained to the conventional methanol/acetic acid method.

The Amyloid fibrils of proteins are involved in various diseases, such as Alzheimer\'s disease. To suppress such amyloid fibrils, it is essential to develop methods to elucidate their enzymatic degradation process. Lysozyme in egg white has been well studied as a model protein of amyloid fibrils. Here, we establish a method for separating and evaluating both lysozyme fibrils and their enzymatic degradation products by combining non-denaturing gel electrophoresis and anionic dye staining with Congo red and two Coomassie brilliant blue (CBB) dyes. By combining non-denaturing gel electrophoresis and amyloid-specific Congo red staining, the separation site of lysozyme fibril was stained explicitly by Congo red and identified on the gel, and the amount of lysozyme fibrils decreased following the enzymatic degradation of lysozyme fibrils. Both lysozyme fibrils and their enzymatic degradation products were separated and examined by combining non-denaturing gel electrophoresis and double staining with CBB G-250 and R-250 dyes. Protein stained with negatively charged colloidal CBB G-250 could migrate to the anode side of electrophoresis. Following gel electrophoresis, noncolloidal CBB R-250 was used to detect lysozyme fibrils and the enzymatic degradation products. This method can be applied to investigate the enzymatic degradation process of amyloid fibrils.

Pulmonary fibrosis (PF) is a life-threatening disorder with a very poor prognosis. Because of the complexity of PF pathological mechanisms, filling such an unmet medical need is challenging. A number of pulmonary diseases have been linked to the activation of NF-κB and the NLRP3 inflammasome. Coomassie brilliant blue G-250 (CBBG) is proved to be a safe highly selective P2×7R antagonist with promising consequent inactivation of NLRP3 inflammasome. This is the first report to investigate the effect of CBBG on the bleomycin-induced lung fibrosis in rats. Our findings revealed that CBBG resulted in a significant improvement in histological features and oxidative status biomarkers of bleomycin-exposed lung tissue. Additionally, CBBG repressed collagen deposition as indicated after the analysis of hydroxyproline, TGF-β, PDGF-BB, TIMP-1, MMP-9, Col1a1, SMA and ICAM-1. It also exhibited anti-inflammatory potential as revealed by the determination of TNF-α, IL-1β, IL-18, MCP-1 in the lung tissue. In the bronchoalveolar lavage, the total protein and the LDH activity were substantially reduced. The lung protective effects of CBBG might be attributed on the one hand to the inhibition of NLRP3 inflammasome and on the other hand to the inactivation of NF-κB. Decreased levels of phospho-p65 and its DNA-binding activity as well as the analysis of TLR4 confirmed NF-κB inactivation. Caspase-1 activity is suppressed as a consequence of inhibiting NLRP3 inflammasome assembly. To conclude, CBBG may act as a primary or adjuvant therapy for the management of PF and therefore it may pose an opportunity for a novel approach to an unmet medical need.

We previously found that multimeric GlyT1aN16 protein exhibits increased diffusion in a polyacrylamide gel and shows an unusual time-dependent absorbance rearrangement, as revealed by the Bradford assay. Here, we find that glycine to alanine mutation eliminates the absorbance shift, but not the altered diffusion properties of GlyT1aN16, indicating that these two phenomena are not interconnected. The absorbance shift is apparent with both native and urea-denatured GlyT1aN16, suggesting that the effect is either not dependent on protein structure, or the required structure is restored very quickly following denaturant removal. In the far-UV spectra, circular dichroism (CD) curves for both wild-type and mutated GlyT1aN16 are under the zero line, indicating largely unstructured character. However, a significant shift of the mutant CD curve suggests possible microstructural heterogeneity. Deconvolution of the CD data indicates a potential 3-fold increase in isolated helical content, which would inhibit an absorbance shift, as we demonstrated previously. These results suggest that, in addition to protein quantification, Coomassie Brilliant Blue G-250 can be used to reveal certain properties of the secondary structure of proteins.

Coomassie Brilliant Blue interacts with proteins and even though the interactions exhibit variation due to the amino acid content, reported dye interactions with individual proteins appear to be relatively stable. Here we report an atypical dynamic interaction of glycine transporters 1 and 2 N-termini with Coomassie dye, resulting in intramolecular interference with their Bradford assay. These proteins exhibit classic protein-Coomassie G-250 complex with absorption maximum at 595 nm, which within minutes starts to decrease and parallel increase of absorbance shoulders above 300 and 700 nm is observed. Interestingly, these effects are eliminated upon fusion of glycine transporters N-termini with glutathione S-transferase protein or by the presence of glutathione S-transferase or bovine serum albumin in the same solution. Circular dichroism data revealed largely unstructured character of glycine transporters N-termini, which suggests that dynamic properties of these protein- Coomassie complexes might be a signature of high flexibility and protein disorder. The assay might potentially reveal similar domains in other proteins and help to associate them with particular functions.