What are the differences between Bradford (HY-K2001, MCE) protein quantification and BCA quantification?
The Bradford assay works best for relatively simple samples in buffers with low SDS content. It offers high sensitivity and a short detection time. The BCA assay, on the other hand, is more tolerant to interfering substances, provides higher quantification accuracy, but generally takes longer to complete.
The answer to this question comes from MCE Technical Support.
I think the differences here are best explained by differences in mechanisms of these assays. Bradford reaction is more direct - the dye interacts directly with protein (so everything that binds to protein will interefere). In case of BCA the reaction is indirect - Cu2+ is reduced to Cu1+ which is later detected by complexing with bicinchoninic acid (BCA... so everything that reduces Cu or chelates it will interfere). Due to this the interfering substances are different for both of these tests. For Bradford the worst are detergents, reducing agents and chaotropes, as for BCA you should really avoid reducing agents, chelators and strong acinds/bases. For the details it is always best to check the compatibility table, usually provided by manufacturer (like here: https://assets.thermofisher.com/TFS-Assets/LSG/Application-Notes/TR0068-Protein-assay-compatibility.pdf)
Hello Yan Yan Zhao
You may be wanting to choose between Bradford protein assay and BCA protein assay that is best for your purpose.
a. You will choose Bradford assay when samples are pure and lack high levels of detergents or reducing agents because Bradford assay is less tolerant of detergents, buffers, and reducing agents, which can interfere or cause precipitation.
b. When high sensitivity is needed, Bradford assay is suitable as this assay is sensitive to protein quantities as low as 1 to 20 μg.
c. When speed is crucial, Bradford assay might be preferred since the entire process typically takes around 5 to 10 minutes.
1. You will choose BCA assay when you have detergents or reducing agents or other substances commonly found in protein samples as this assay is versatile and is applicable to a wider range of sample types.
2. When you are working with samples with a wide range of concentrations, consider the BCA assay as this protocol is suitable for protein
concentrations ranging from 20 to 2,000 µg/ml.
3. When time is not a constraint, you may think of working with BCA assay as this assay requires longer incubation time (for 30 minutes at 37°C or at room temperature for 2 hours).
Best,
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