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Protein BCA Assay (Kit)
The principle of the bicinchoninic acid (BCA) assay is similar to the Lowry procedure, in that both rely on the formation of a Cu2+-protein complex under alkaline conditions, followed by reduction of the Cu2+ to Cu1+. The amount of reduction is proportional to the protein present. In the second step, BCA forms a purple colored complex with Cu+1, which is detectable at 562 nm.
Protein + Cu2+ => Cu1+ + BCA => Cu1+- BCA complex
It has been shown that cysteine, cystosine, tryptophan, tyrosine, and the peptide bond are able to reduce Cu2+ to Cu1+. BCA forms a purple-blue complex with Cu1+ in alkaline environments, thus providing a basis to monitor the reduction of alkaline Cu2+ by proteins at absorbance maximum 562 nm.
SPECIAL FEATURES
- Simple and sensitive in protein assays.
- Faster and easier than Lowry protein assay.
- Compatible with many ionic and nonionic detergents.
- Independent of specific amino acid content of proteins.
- Accurate over a wide range of protein concentrations.
KIT CONTENTS
- BCA Protein Assay Reagent 1: 750ml
- BCA Protein Assay Reagent 2: 25ml
- Protein Standard Solution: 10ml
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A special note for using BCA Protein Assay:
BCA Protein Assayis compatible with many ionic and nonionic detergents at levels up to 5%. BCA Protein Assay is also less complicated to perform than the Lowry Protein Assay . In addition, it produces a nearly linear response curve across a wide range of protein concentrations. The standard BCA Protein Assay detects protein from 20-2,000 µg/ml. The Low Protein BCA Assay (G1003) has a narrower dynamic range of 1-100 µg/ml.
Care needs to be taken with protein solutions containing reducing substances or chelating reagents. Substances that reduce copper will interfere with the accuracy of the protein quantitation; and reagents that chelate copper will reduce the amount of Cu1+- BCA complex formed during the reaction. When this is the case, use the Bradford Protein Assay (G1001).
REFERENCES
- Smith, PK, et al., 1985, Measurement of protein using bicinchoninic acid. Anal Biochem. Oct;150(1):76-85.
- Stoscheck, C. 1990,Quantification of Protein. Methods in Enzymology, 182:50-68.
- Lowry, O., et al., 1951, Protein measurement with the Folin phenol reagent. J. Biol.Chem.193:265-275.