Thermo Scientific™ Pierce™ Bradford Plus Protein Assay Kits

Product Code.	Concentration	unitSize
18011663	BSA: 0.125, 0.25, 0.5, 0.75, 1, 1.5, and 2 mg/mL	950mL
10741945	BSA: 2 mg/mL	960mL

Product Code. 18011663 Supplier Thermo Scientific™ Supplier No. A55866

Description

The Pierce Bradford Plus Protein Assay Kit is a ready-to-use, reducing agent-compatible, improved Bradford assay reagent used to quickly measure total protein concentration compared to a protein standard.

The Pierce Bradford Plus Protein Assay Kit is a ready-to-use, reducing agent-compatible, improved Bradford assay reagent used to quickly measure total protein concentration compared to a protein standard. It provides increased linearity and half the protein-to-protein variability of other commercial Bradford assay formulations.

Kits are available with or without Pierce Dilution-Free BSA Protein Standards, which are a set of seven pre-diluted BSA standards, packaged in a multichannel pipette-friendly tubestrip. The tubestrip includes a single empty tube that enables users to add their own sample buffer for the purpose of blank subtraction.

The Pierce Bradford Plus Protein Assay Kit is a ready-to-use, reducing agent-compatible, improved Bradford assay reagent used to quickly measure total protein concentration compared to a protein standard. It provides increased linearity and half the protein-to-protein variability of other commercial Bradford assay formulations.

Kit options include Pierce Dilution-Free BSA Protein Standards, which are a set of seven pre-diluted BSA standards, packaged in a multichannel pipette-friendly tubestrip. The tubestrip includes a single empty tube that enables users to add their own sample buffer for the purpose of blank subtraction.

Features of the Pierce Bradford Plus Protein Assay Kit include:

• Colorimetric—measure with a standard spectrophotometer or plate reader at 595 nm
• Easy to use—single reagent; no working reagent preparation required
• Fast—almost immediate color development; add, mix, and read results
• Wide assay range—detects protein concentration in the range 1 to 1500 μg/mL
• Linear—improved linearity and response uniformity compared to traditional Bradford formulations
• Flexible—microplate and cuvette protocols provided and adaptable to several target working ranges
• Serial dilution–free—select kit options include Dilution-Free BSA Protein Standards that eliminate the need to perform serial dilutions when generating a standard curve

The assay is performed at room temperature. Simply add the sample to the tube or well containing reagent, and the resultant blue color is measured at 595 nm following a short room-temperature incubation. The protein assay is compatible with most salts, solvents, buffers, thiols, reducing substances, and metal-chelating agents encountered in protein samples. The assay can be performed in either test tube or microplate format.

How the Bradford Plus Assay detects protein

Use of Coomassie G-250 dye in a colorimetric reagent for the detection and quantitation of total protein was first described by Dr. Marion Bradford in 1976. In the acidic environment of the reagent, protein binds to the Coomassie dye. This results in a spectral shift from the reddish/brown form of the dye (absorbance maximum at 465 nm) to the blue form of the dye (absorbance maximum at 610 nm). The difference between the two forms of the dye is greatest at 595 nm, so that is the optimal wavelength to measure the blue color from the Coomassie dye-protein complex. If desired, the blue color can be measured at any wavelength between 575 nm and 615 nm. At the two extremes (575 nm and 615 nm) there is a loss of about 10% in the measured amount of color (absorbance) compared to that obtained at 595 nm.

Development of color in Coomassie dye-based (Bradford) protein assays has been associated with the presence of certain basic amino acids (primarily arginine, lysine, and histidine) in the protein. Van der Waals forces and hydrophobic interactions also participate in the binding of the dye by protein. The number of Coomassie dye ligands bound to each protein molecule is approximately proportional to the number of positive charges found on the protein. Free amino acids, peptides, and low molecular weight proteins do not produce color with Coomassie dye reagents. In general, the mass of a peptide or protein must be at least 3000 Daltons to be assayed with this reagent.

Specifications

• Concentration: BSA: 0.125, 0.25, 0.5, 0.75, 1, 1.5, and 2 mg/mL
• Content And Storage: Sufficient for: 630 tube assays or 3160 microplate assays
  • Pierce Bradford Plus Assay Reagent, 950 mL
  • Dilution-Free BSA Protein Standards (0.125-2 mg/mL), 2 x 1 mL 8-channel tubestrip
  Store Bradford Plus Assay Reagent at 4°C.
• Assay: Bradford Assay
• Detection Method: Colorimetric
• Product Line: Pierce
• Product Type: Protein Quantitation Assay
• Specificity: Not Target-specific
• Sufficient For: 630 Tube Assays or 3160 Microplate Assays
• For Use With (Application): Solution-based Detection, Absorbance
• For Use With (Equipment): Spectrophotometer, Microplate Reader
• Kit Contents: 2 x 1 mL 8-channel tubestrip, prediluted, dilution-Free BSA protein standards
• Quantity: 950 mL

Frequently Asked Questions (FAQs)

What is the difference between the Pierce Dilution-Free BSA Protein Standards that come with the Pierce Bradford Plus Protein Assay Kit and the Pierce Bovine Serum Albumin Standard Ampules, 2 mg/mL (Cat. No. 23209)?

Pierce Dilution-Free BSA Protein Standards are provided in a convenient 8-channel tubestrip. Each tube contains 1 mL of pre-diluted BSA protein standard at each concentration required for generating a standard curve. In the Pierce Bradford Plus Protein Assay Kit with Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible (Cat. No. A55866), the BSA concentrations included are 2000, 1500, 1000, 750, 500, 250, and 125 µg/mL. Each tubestrip contains one empty tube which allows the user to add their own blank solution for the purpose of background correction. This convenient format eliminates the time-consuming dilution step required for other single-concentration protein standard formats like the Pierce Bovine Serum Albumin Standard Ampules, 2 mg/mL (Cat. No. 23209).

Additionally, the tubestrips are compatible with multichannel pipettes which allows the user to easily transfer the full standard curve dilution series (including blank) to a microplate simultaneously. This minimizes pipetting time associated with traditional protein standard preparation or pre-diluted protein standards which are typically packaged in 7 separate vials, requiring the user to open each vial and pipette each standard individually.

How does the Pierce Bradford Plus Protein Assay Kit with Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible compare with the original Pierce Bradford Plus Protein Assay Kit (Cat. No. 23236)?

The Pierce Bradford Plus Protein Assay Kit with Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible (Cat. No. A55866) includes the same assay reagent as the Pierce Bradford Plus Protein Assay Kit (Cat. No. 23236), formerly called the Pierce Coomassie Plus (Bradford) Assay Kit. The only difference between the two products is the BSA protein standard format. While the Pierce Bradford Plus Protein Assay Kit (Cat. No. 23236) includes the Pierce Bovine Serum Albumin Standard Ampules, 2 mg/mL (Cat. No. 23209), the Pierce Bradford Plus Protein Assay Kit with Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible (Cat. No. A55866) includes BSA protein standards that are pre-diluted and packed in a convenient, multichannel pipette-friendly format. This format provides the following advantages:

-No protein standard dilution step needed
-High-throughput (multichannel pipette compatible)
-Blank tube provided for background correction
-Reduced hands-on assay time
-Reduced chances for pipetting errors

Can I purchase the Pierce Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible included in the Pierce BCA Protein Assay Kit with Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible as a standalone item?

Yes, the Pierce Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible, 0.125-2 mg/mL can be purchased separately (Cat. No. A55863).

If we are assaying immunoglobin samples, do you offer bovine gamma globulin (BGG) protein standards in the Dilution-Free format?

We currently do not offer bovine gamma globulin (BGG) protein standards in the same multichannel pipette compatible format as the Pierce Dilution-Free BSA Protein Standards. They are only available as Pierce Bovine Gamma Globulin Standard Ampules, 2 mg/mL (Cat. No. 23212) and Pierce Bovine Gamma Globulin Standard Pre-Diluted Set (Cat. No. 23213).

Is the BSA in the Pierce Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible the same as the BSA standards found in other Pierce protein assays and Pierce BSA protein standard products?

The BSA in the Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible included in the Pierce Dilution-Free Rapid Gold BCA Protein Assay Kit (Cat. No. A55860, A55861, A55862) is identical to the BSA included in the Pierce Rapid Gold BCA Protein Assay Kit (Cat. No. A53225, A53226, A53227). It is also identical to the BSA found in Pierce Bovine Serum Albumin Standard Ampules, 2 mg/mL (Cat. No. 23209) and the Pierce Bovine Serum Albumin Standard Pre-Diluted Set (Cat. No. 23208).

How can I prevent contamination of the Pierce Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible?

To ensure that the BSA standards remain free of contaminants, we recommend minimizing the time the tubestrips are uncovered/uncapped. Immediately place the capstrip over the tubes after each use. Be sure to press the caps firmly when closing so that it fits snugly. Store the Pierce Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible at 4 degrees C.

What is the orientation of the Pierce Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible?

For Pierce Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible, the tubestrip has a single printed label on the top-center of the first tube indicating the tube containing the 2 mg/mL concentration (for Cat. No. A55863) or 10 mg/mL concentration (for Cat. No. A56979). Each subsequent tube contains the next highest concentration in the dilution series. The end-tube opposite the printed label is left empty to allow the user to add their own blank solution for the purpose of background correction. On the capstrip, there is a small hole at one end that can be used to orient the caps. When placing the caps on the tubestrip, we recommend aligning the hole-side of the capstrip with the labeled side of the tubestrip.

How do I open the Pierce Dilution-Free tubestrips?

To access the BSA standards, hold one side of the tubestrip firmly and carefully pull the foil seal to remove it from the tubestrip. The standards come with a capstrip for convenient closing and storage between uses.

What is the shelf-life of the Pierce Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible?

The Pierce Dilution-Free BSA Protein Standards, Multichannel Pipette Compatible are covered under our general 1-year warranty and are guaranteed to be fully functional for 12 months from the date of shipment if stored as recommended. The product should be stored at 4 degrees C after opening. Please see section 8.1 of our Terms & Conditions of Sale (https://www.thermofisher.com/content/dam/LifeTech/Documents/PDFs/Terms-and-Conditions-of-Sale.pdf).

For Research Use Only.