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BCA Protein Assay Reagent (bicinchoninic acid)


Used in more labs than any other detergent-compatible protein assay.

Pierce BCA Protein Assay Kit

The Thermo Scientific Pierce BCA Protein Assay Kit is a two-component, high-precision, detergent-compatible assay reagent set to measure (A562nm) total protein concentration compared to a protein standard.

Used in more labs than any other detergent-compatible protein assay, Pierce BCA Reagents provide accurate determination of protein concentration with most sample types encountered in protein research. The Pierce BCA Assay can be used to assess yields in whole cell lysates and affinity-column fractions, as well as to monitor protein contamination in industrial applications. Compared to most dye-binding methods, the BCA Assay is affected much less by protein compositional differences, providing greater protein-to-protein uniformity.

Highlights:

  • Colorimetric – estimate visually or measure with a standard spectrophotometer or plate reader (562nm)
  • Excellent uniformity – exhibits less protein-to-protein variation than dye-binding methods
  • Compatible – unaffected by typical concentrations of most ionic and nonionic detergents
  • Moderately fast – much easier and four times faster than the classical Lowry method
  • High linearity – linear working range for BSA equals 20 to 2000µg/mL
  • Sensitive – detect down to 5µg/mL with the enhanced protocol

Applications:

  • Studying protein:protein interactions
  • Measuring column fractions after affinity chromatography
  • Estimating percent recovery of membrane proteins from cell extracts
  • High-throughput screening of fusion proteins

Product Details:

Video of the Pierce BCA Protein Assay Kit in action!

 

Typical standard curves for the Pierce BCA Protein Assay
Standard curves. Typical standard curves for bovine serum albumin (BSA) and bovine gamma globulin (BGG) in the BCA Protein Assay. Kits include ampules of Albumin Standard.

 

Time comparison of BCA Protein Assay Reagent vs. Lowry Protein Assay.
BCA Protein Assay Reagent Lowry Protein Assay
  1. Mix reagents 1 minute
  2. Add sample and incubate 30 minutes
  3. Read at 562nm 1 minute
  1. Make reagents 70 minutes
  2. Add sample and incubate 20 minutes
  3. Add Folin Reagent 1 minute
  4. Incubate 30 minutes
  5. Read at 750nm 1 minute
Total BCA Time: 32 minutes

Total Lowry Time: 122 minutes

How the BCA Protein Assay Detects Protein:

The BCA Protein Assay combines the well-known reduction of Cu2+ to Cu1+ by protein in an alkaline medium with the highly sensitive and selective colorimetric detection of the cuprous cation (Cu1+) by bicinchoninic acid. The first step is the chelation of copper with protein in an alkaline environment to form a light blue complex. In this reaction, known as the biuret reaction, peptides containing three or more amino acid residues form a colored chelate complex with cupric ions in an alkaline environment containing sodium potassium tartrate.

In the second step of the color development reaction, bicinchoninic acid (BCA) reacts with the reduced (cuprous) cation that was formed in step one. The intense purple-colored reaction product results from the chelation of two molecules of BCA with one cuprous ion. The BCA/copper complex is water-soluble and exhibits a strong linear absorbance at 562 nm with increasing protein concentrations. The BCA reagent is approximately 100 times more sensitive (lower limit of detection) than the pale blue color of the first reaction.

The reaction that leads to BCA color formation is strongly influenced by four amino acid residues (cysteine or cystine, tyrosine, and tryptophan) in the amino acid sequence of the protein. However, unlike the Coomassie dye-binding methods, the universal peptide backbone also contributes to color formation, helping to minimize variability caused by protein compositional differences.

For more information, see the article "Chemistry of Protein Assays" in the Protein Methods Library.

References:

  1. Smith, P.K., et al. (1985). Anal. Biochem. 150: 76-85.
  2. Sorensen, K. (1992). BioTechniques 12(2): 235-236.
  3. Ju, T., et. al. (2002). J. Biol. Chem. 277: 178-186.
  4. Shibuya, T., et. al. (1989). Tokyo Ika Daigaku Zasshi 47(4): 677-682.
  5. Hinson, D.L. and Webber, R.J. (1988). BioTechniques 6(1): 14-19.
  6. Akins, R.E. and Tuan, R.S. (1992). BioTechniques 12(4): 496-499.
  7. Tylianakis, P.E., et. al.(1994). Anal. Biochem. 219(2): 335-340.
  8. Gates, R.E. (1991). Anal. Biochem. 196(2): 290-295.
  9. Stich, T.M. (1990). Anal. Biochem. 191: 343-346.
  10. Tuszynski, G.P. and Murphy, A. (1990). Anal. Biochem. 184(1): 189-191.

Related Resources:

BCA Protein Assay Reagents FAQ
Protein Assay Selection Guide
Protein Assay Compatibility Table

Protein Methods Library:

Overview of Protein Assays
Chemistry of Protein Assays
Protein Assay Data Analysis

Compatible Instrumentation:

BioMate 3 UV-Vis Spectrophotometer
NanoDrop 2000c UV/Vis Spectrophotometer
NanoDrop 8000 UV/Vis 8 Sample Spectrophotometer

Related Products:

BSA Assay StandardsBGG Assay Standards
Coomassie, Pierce 660nm, and Other Assay Reagents
Microplates for Protein Assays


Ordering Information
 
Product # Description Pkg. Size Instructions MSDS CofA Price
23225 BCA Protein Assay Kit
Formulation: Multi-component kit
Sufficient For: 500 tube assays or 5000 microplate assays

Kit Contents:
BCA Reagent A, 2 x 500mL
BCA Reagent B, 25mL
Albumin Standard Ampules, 2mg/mL, 10 x 1mL
1L kit Product Instructions for product #23225 BCA Protein Assay Kit MSDS for product #23225 BCA Protein Assay Kit Certificate of Analysis for product #23225 BCA Protein Assay Kit $171.00

Add to cart
23227 BCA Protein Assay Kit
Formulation: Multi-component kit
Sufficient For: 250 tube assays or 2500 microplate assays

Kit Contents:
BCA Reagent A, 500mL
BCA Reagent B, 25mL
Albumin Standard Ampules, 2mg/mL, 10 x 1mL
500mL kit Product Instructions for product #23227 BCA Protein Assay Kit MSDS for product #23227 BCA Protein Assay Kit Certificate of Analysis for product #23227 BCA Protein Assay Kit $110.00

Add to cart
23221 BCA Protein Assay Reagent A
Formulation: Bicinchonic acid and tartrate in an alkaline carbonate buffer
Sufficient For: 1250 microplate assays when mixed with Reagent B
250mL MSDS for product #23221 BCA Protein Assay Reagent A Certificate of Analysis for product #23221 BCA Protein Assay Reagent A $56.00

Add to cart
23228 BCA Protein Assay Reagent A
Formulation: Bicinchonic acid and tartrate in an alkaline carbonate buffer
Sufficient For: 2500 microplate assays when mixed with Reagent B
500mL MSDS for product #23228 BCA Protein Assay Reagent A Certificate of Analysis for product #23228 BCA Protein Assay Reagent A $82.00

Add to cart
23223 BCA Protein Assay Reagent A
Formulation: Bicinchonic acid and tartrate in an alkaline carbonate buffer
Sufficient For: 5000 microplate assays when mixed with Reagent B
1L MSDS for product #23223 BCA Protein Assay Reagent A Certificate of Analysis for product #23223 BCA Protein Assay Reagent A $124.00

Add to cart
23222 BCA Protein Assay Reagent A
Formulation: Bicinchonic acid and tartrate in an alkaline carbonate buffer
Sufficient For: 18,750 microplate assays when mixed with Reagent B
3.75L MSDS for product #23222 BCA Protein Assay Reagent A Certificate of Analysis for product #23222 BCA Protein Assay Reagent A $425.00

Add to cart
23224 BCA Protein Assay Reagent B
Formulation: 4% copper sulfate pentahydrate solution
Sufficient For: 5000 microplate assays when mixed with Reagent A
25mL MSDS for product #23224 BCA Protein Assay Reagent B Certificate of Analysis for product #23224 BCA Protein Assay Reagent B $43.00

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23230 BCA Solid
Formulation: Bicinchonic acid as a recrystallized pure powder
Sufficient For: Preparing 2.5L of Reagent A
25g MSDS for product #23230 BCA Solid Certificate of Analysis for product #23230 BCA Solid $305.00

Add to cart
23230B BCA Solid
Formulation: Bicinchonic acid as a recrystallized pure powder
Custom MSDS for product #23230B BCA Solid Certificate of Analysis for product #23230B BCA Solid

Instructions | MSDS | CofA
Product Instructions | MSDS | CofA  

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