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Invitrogen™ Qubit™ Protein and Protein Broad Range (BR) Assay Kits
Description
Quantify protein quickly and accurately with two unique Qubit protein quantification kits: the Qubit Protein Assay, which quantifies 12.5 μg/mL to 5 mg/mL of protein, and the Qubit Protein BR Assay Kit, which quantifies 0.1 to 20 mg/mL of protein. Both assays are compatible with many common contaminants, reducing reagents, salts, and nucleic acids. The Protein BR Assay Kit is also tolerant of detergents.
The Qubit Protein Assay Kit is designed specifically for use with any Qubit fluorometer. While using between 1 and 20 μL of sample, this assay can quantify samples ranging from 12.5 μg/mL to 5 mg/mL with low protein-to-protein variation.
The Qubit Protein Assay Kit is highly selective for proteins and is also highly accurate in the presence of reducing reagents, but not in the presence of large amounts of detergent. Common contaminants, such as reducing reagents (e.g., DTT, β-mercaptoethanol), salts, free nucleotides, amino acids, solvents, and DNA (but not detergents), are well tolerated in the assay. Slight protocol modifications are required for other contaminants.
The kit provides concentrated assay reagent, dilution buffer, and pre-diluted BSA standards. Simply dilute the reagent using the buffer provided, add your sample (any volume between 1 μL and 20 μL is acceptable), and read the concentration.
Which product should you choose for fluorometric protein quantitation?
• 1–20 samples: use this Qubit Protein Assay Kit with the Qubit Fluorometer
• 20–2000 samples: use the Quant-iT Protein Assay Kit with a microplate reader
Qubit Protein BR Assay Kit
The Qubit Protein BR Assay Kit provides a quick, easy, and reliable method for determining the protein concentration of purified proteins, lysates, serum, plasma, or complex protein mixtures using a Qubit 4 Fluorometer. This protein kit can deliver accurate protein quantitation across a broad range (0.1–20 mg/mL), enabling most samples to be used neat (undiluted) and eliminating the guess work and dilution steps that accompany traditional protein quantitation methods. The assay is compatible with many common contaminants, such as detergents, reducing reagents (e.g., DTT, β-mercaptoethanol), salts, and nucleic acids.
Key features of the Qubit Protein BR Assay Kit include:
• Broad dynamic range—0.1 to 20 mg/mL, measure samples without dilution
• Two-point standard curve—eliminate time-consuming standard preparation
• Automatic concentration determination—receive protein concentration instantaneously; no need for offline calculations
• Compatible—accurate in the presence of reducing reagents, detergents, and other common buffer components
The Qubit Protein BR Assay Kit comes with two calibration standards, Protein BR Assay Buffer, and Protein BR Assay Reagent. Simply add 150–160 μL of Protein BR Assay Buffer to 10 or 20 μL of your sample, followed by 30 μL of Protein BR Assay Reagent. Incubate for 10 minutes at room temperature. Then insert the sample into a Qubit 4 instrument and read the concentration.
Notes
• The Qubit Protein Assay Kit can be used with Qubit 1.0, Qubit 2.0, Qubit 3, and Qubit 4 fluorometers
• The Qubit Protein BR Assay Kit is a fluorescence-based assay intended for use only with the Qubit 4 Fluorometer
• 500 μL thin-walled clear PCR tubes (Cat. No. Q32856) are required but not included in the Protein Assay and BR Assay Kits
Specifications
Specifications
| Assay | Qubit Protein Broad Range Assay |
| Detection Method | Fluorescence |
| Product Line | Qubit |
| Product Type | Protein BR Assay Kit |
| Sufficient For | 100 Reactions |
| For Use With (Equipment) | Qubit 4 Fluorometer |
| Quantitation Range | 0.1 to 20 mg/mL |
| Quantity | 100 Assays |
| Shipping Condition | Wet Ice |
Frequently Asked Questions (FAQs)
The concentration of detergents in 1x RIPA buffer is quite high, therefore, we do not recommend that you use this kit with samples in RIPA. The Qubit Protein Assay has a tolerance for detergents present only in very low amounts. Please see the user guide for the tolerance of this assay for detergents here. The Qubit Protein Broad Range (BR) Assay Kit (A50668) has a much higher tolerance for detergents, e.g. RIPA buffer can be used undiluted. Please see this link.
To be able to use the Qubit Protein Broad Range Assay (Cat. No. A50668) on the Qubit 4 Fluorometer (Cat. No Q33238) you would need to install the latest firmware on the fluorometer. Please find the latest Qubit 4 firmware (v2.19) on the following webpage: https://downloads.thermofisher.com/Qubit4/v2.19/Qubit4_update_v2.19.pak Save the firmware update on a USB stick and upload it to the Qubit 4 Fluorometer. Once the firmware update has been installed, you will be able to see the Protein BR assay on the Qubit 4 Fluorometer.
Though the Quant-iT Protein Assay Kit is indicated for high-throughput application, it is completely separate from the Qubit Protein and Protein Broad Range Assay Kits, not another version of them.
No, the Quant-it and Qubit reagents use different dyes and therefore are not interchangeable.
To access “Protein Broad Range” in the “Protein” menu of your Qubit 4 instrument, as instructed in the Qubit Protein BR Assay Kit (Cat. Nos. A50668, Q33211, Q33212, A50669) instructions, the instrument will require the latest firmware update (v2.19 or v1.8.0 for the Qubit Flex). You can check which version you currently have on your device by clicking on "Settings" from the Home screen, and then on "About Instrument".
To update the software:
Download the latest firmware update from the Qubit Fluorometers Technical Resources page.
Follow the instructions for updating your Qubit instrument in the firmware Release notes or in the Qubit 4 Fluorometer User Guide (page 53).
After the update has been completed, the option "Protein Broad Range" should become available.
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