The SMART™ BCA protein assay kit(for Standard Assay) is a detergent-compatible formulation based on bicinchoninic acid(BCA) for the colorimetric detection and quantitation of total protein. The purple-colored reaction product of this assay is formed by the chelation of two molecules of BCA with one cuprous ion. This water-soluble complex exhibits a strong absorbance at 562 nm that is nearly linear with increasing protein concentrations over a broad working range. (20-2,000 ug/ml)
The macromolecular structure of protein, the number of peptide bonds and the presence of four particular amino acids(cystein, cystine, tryptophan and tyrosine)are reported to be responsible for color formation with BCA. Studies with di-, tri- and tetrapeptides suggest that the extent of color formation caused by more than the mere sum of individual colorproducing functional groups. Accordingly, protein concentrations generally are determined and reported with reference to standards of a common protein such as bovine serum albumin (BSA). A series of dilutions of known concentration are prepared from the protein and assayed alongside the unknown(s) before the concentration of each unknown is determined based on the standard curve.
Two assay procedures are presented. Of these, the Test Tube Procedure requires a larger volume(0.1ml) of protein sample; however, because it uses a sample to working solution ratio of 1:20(v/v), the effect of interfering substances minimized. The Microplate Procedure affords the sample handling ease of a microplate and requires a smaller volume (10-25 ul) of protein sample; however, because the sample to working solution ratio is 1:8 (v/v), it offers less flexibility in overcoming interfering substance concentrations and obtaining low levels of detection.
-Colorimetric method; read at 562 nm
- Compatible with most ionic and nonionic detergents
- Faster and easier than the lowry method
- All reagents stable at room temperature for 2 years
- Working solution stable for 24 hours
- Linear working range for BSA: 20-2,000 ug/ml
- Adaptable to microplates
- Less protein-to-protein variation than dye-binding methods
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* Solution A
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250 ㎖x 2 ea
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* Solution B
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10 ㎖
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* BSA solution (2mg/ml)
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1 ㎖ x 10 ea
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Storage at RT
(If either Solution A or Solution B precipitates upon shipping in cold weather or during long-term storage, dissolve precipitates by gently warming and stirring solution. Discard any kit reagent that shows discoloration or evidence of contamination. ) |
 Improved sensitivity & Linear working range
Fig. 1. Comparison of sensitivity of protein assay
SMARTTM BCA Protein Assay Kit (for Standard Assay) shows improved sensitivity higher than competitor product as 15-20%.
The color response was estimated micro well plate reader (37℃/30 minute incubation)
Fig. 2. Typical color response curves for BSA, Chymotrypsin and Lysozyme using the Microplate Protocol.
Absorbance ratios (562 nm) for proteins relative to BSA. The SMARTTM BCA Protein Assay Kit (for Standard Assay) showed higher sensitivity (slope) than Competitor. However, The Protien-to-Protein variations showed similar patters.
A; SMARTTM BCA Protein Assay Kit, B; Competitor A Product | 
