An improved Coomassie Dye based protein assay based on the Bradford Protein Assay (1). This assay is suitable for the simple and rapid estimation of protein concentration. This assay is based on a single Coomassie dye based reagent. The binding of protein to the dye results in a change of color from brown to blue. The change in color density is proportional to protein concentration. Protein estimation can be performed using as little as 0.5µg protein
CB™ Protein Assay is supplied with a simple to follow protocol. Ready to use reagent that does not require prefiltering or dilution. Simply mix the protein solution with CB™ Protein Dye and read optical density.
The protein-dye complexes reach a stable end point in 5 minutes. The CB™ Protein Assay is compatible with reducing agents and a wide variety of common laboratory agents listed below. The assay is supplied with a traditional bovine serum albumin (BSA) protein standard or a non animal protein standard.
Note: The Coomassie dye based assay is not suitable if the protein solution contains higher than recommended concentration of detergents or other agents (see Table 1). Tolerance to Common laboratory Agents The following table kists the agents compatible with the CB™ Protein Assay. Table 1 also shows the acceptable concentration of reagents for standard protocols. In most cases, using a correct blank will eliminate or minimize the error caused by interference.
Table 1: A selection of compounds and the maximum concentrations that are compatible with the CB™ Assay.| Compound | Concentration | Compound | Concentration | Compound | Concentration |
| Amino acids | 1mM | DTT | 1M | Phenol | 5% |
| Ammonium sulfate | 1M | EDTA | 100mM | Sodium azide | 0.5% |
| Ampholytes | 0.5% | EGTA | 50mM | Sodium chloride | 6M |
| Ascorbic acid | 50mM | Ethanol | 10% | Sodium dodecyl sulfate (SDS) | 0.015% |
| Boric acid | 1mM | Glucose | 1M | Sodium hydroxide | 0.1M |
| Brij® 35 | 0.06% | Glycerol | 10% | Sodium phosphate | 0.1M |
| CHAPS | 0.5% | Glycine | 0.1M | Sucrose | 25% |
| CHAPSO | 0.5% | Guanidine.HCl | 6M | Tris | 2M |
| Citrate | 0.05% | HEPES | 0.1M | Triton® X-100 | 0.06% |
| Cysteine | 10mM | 2-mercaptoethanol | 1M | tRNA | 0.35mg/ml |
| Deoxycholate | 0.1% | Methanol | 10% | Tween® 20 | 0.03% |
| DMSO | 10% | MES | 0.7M | Urea | 3M |
| DNA | 1mg/ml | Nonidet® P-40 | 0.5% |
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Features
- Sensitivity: Linear responses over the range of 0.5µg-50µg protein
- Flexible Protocols: Suitable for tube or Titer plate assays
- Ready to use assay reagents and no preparation required
- Long shelf life, stable for 12 months
Applications
- Suitable for non-detergent solubilized proteins.
- Protein estimation in protein purification, electrophoresis, cell biology, molecular biology, and other research applications.
- Suitable for protein samples containing common laboratory agents.