After protein extraction, protein quantification is required. The three commonly used methods are BCA (bicinchoninic acid), Bradford (Coomassie), and Lowry methods, which can be used to determine protein concentrations in samples with different buffer compositions.
Comparison Table of Characteristics and Differences of Three Protein Quantification A ssay Kits
The BCA method is currently one of the most widely used protein concentration determination methods. Its principle is based on the biuret reaction. Under alkaline conditions, peptide bonds in protein molecules form complexes with Cu²⁺ and reduce Cu²⁺ to Cu⁺. BCA reagent specifically binds to Cu⁺ to form a stable colored complex with maximum absorbance at 562 nm. The intensity of the color is proportional to the protein concentration, allowing protein quantification based on absorbance at 562 nm. The BCA protein assay offers simplicity, sensitivity, speed, and stability for protein concentration determination.
| Cat. No. | Description | Packaging |
| BL521S | BCA Protein Assay Kit | 200T |
| BL521A | BCA Protein Assay Kit | 500T |
| BL521B | BCA Protein Assay Kit | 2500T |
| BL521C | BCA Protein Assay Kit | 5000T |
| BL1054S | BCA Protein A ssay Kit (Enhanced) | 200T |
| BL1054A | BCA Protein A ssay Kit (Enhanced) | 500T |
| BL1054B | BCA Protein A ssay Kit (Enhanced) | 2500T |
| BL1054C | BCA Protein Assay Kit (Enhanced) | 5000T |
| BL1673A | Rapid BCA Protein Assay Kit | 100mL |
| BL673A | BSA Protein Standard (5 mg/mL) | 1mL |
The principle of the Bradford method is based on the binding of Coomassie Brilliant Blue G-250 to basic and aromatic amino acids, particularly arginine, in an acidic medium. This binding shifts the solution color to blue, with the maximum absorbance peak shifting from 465 nm to 595 nm. The color change is proportional to the protein concentration, allowing protein quantification by measuring absorbance at 595 nm. The Bradford method is the fastest and simplest protein concentration determination method.
Cat. No. | Description | Packaging |
BL524A | Bradford Protein Assay Kit | 250mL |
BL1434A | Bradford Protein Assay Kit (Detergent-Compatible) | 800T |
The Lowry method is the most sensitive protein concentration determination method. Its principle involves the binding of peptide bonds in proteins with copper ions to form a complex, which reacts with Folin-Ciocalteu reagent to produce a blue color. The absorbance is measured at 750 nm using spectrophotometry (microplate reader or spectrophotometer), and the concentration of the protein sample is determined by comparison with a standard curve. It exhibits good linearity in the concentration range of 1‒1500 μg/mL.
| Cat. No. | Description | Packaging |
| BL367A | Modified Lowry Protein Assay Kit | 500T |
| BL367B | Modified Lowry Protein Assay Kit | 1000T |
After protein extraction, protein quantification is required. The three commonly used methods are BCA (bicinchoninic acid), Bradford (Coomassie), and Lowry methods, which can be used to determine protein concentrations in samples with different buffer compositions.
Comparison Table of Characteristics and Differences of Three Protein Quantification A ssay Kits
The BCA method is currently one of the most widely used protein concentration determination methods. Its principle is based on the biuret reaction. Under alkaline conditions, peptide bonds in protein molecules form complexes with Cu²⁺ and reduce Cu²⁺ to Cu⁺. BCA reagent specifically binds to Cu⁺ to form a stable colored complex with maximum absorbance at 562 nm. The intensity of the color is proportional to the protein concentration, allowing protein quantification based on absorbance at 562 nm. The BCA protein assay offers simplicity, sensitivity, speed, and stability for protein concentration determination.
| Cat. No. | Description | Packaging |
| BL521S | BCA Protein Assay Kit | 200T |
| BL521A | BCA Protein Assay Kit | 500T |
| BL521B | BCA Protein Assay Kit | 2500T |
| BL521C | BCA Protein Assay Kit | 5000T |
| BL1054S | BCA Protein A ssay Kit (Enhanced) | 200T |
| BL1054A | BCA Protein A ssay Kit (Enhanced) | 500T |
| BL1054B | BCA Protein A ssay Kit (Enhanced) | 2500T |
| BL1054C | BCA Protein Assay Kit (Enhanced) | 5000T |
| BL1673A | Rapid BCA Protein Assay Kit | 100mL |
| BL673A | BSA Protein Standard (5 mg/mL) | 1mL |
The principle of the Bradford method is based on the binding of Coomassie Brilliant Blue G-250 to basic and aromatic amino acids, particularly arginine, in an acidic medium. This binding shifts the solution color to blue, with the maximum absorbance peak shifting from 465 nm to 595 nm. The color change is proportional to the protein concentration, allowing protein quantification by measuring absorbance at 595 nm. The Bradford method is the fastest and simplest protein concentration determination method.
Cat. No. | Description | Packaging |
BL524A | Bradford Protein Assay Kit | 250mL |
BL1434A | Bradford Protein Assay Kit (Detergent-Compatible) | 800T |
The Lowry method is the most sensitive protein concentration determination method. Its principle involves the binding of peptide bonds in proteins with copper ions to form a complex, which reacts with Folin-Ciocalteu reagent to produce a blue color. The absorbance is measured at 750 nm using spectrophotometry (microplate reader or spectrophotometer), and the concentration of the protein sample is determined by comparison with a standard curve. It exhibits good linearity in the concentration range of 1‒1500 μg/mL.
| Cat. No. | Description | Packaging |
| BL367A | Modified Lowry Protein Assay Kit | 500T |
| BL367B | Modified Lowry Protein Assay Kit | 1000T |
