Question

bradford assay - microcredentials

1. what is the main principle of the bradford assay?

a. measurement of protein fluorescence intensity
b. binding of coomassie brilliant blue dye to proteins
c. reduction of copper ions by peptide bonds
d. reaction of proteins with the folin - ciocalteu reagent

1. which color change occurs when the dye binds to proteins?

a. blue → red b. brown → blue
c. yellow → brown d. green → purple

1. what is the absorbance wavelength measured in the bradford assay?

a. 280 nm b. 540 nm c. 595 nm d. 750 nm

1. the bradford assay is most sensitive in which protein concentration range?

a. 0.001 - 0.01 μg/ml b. 1 - 100 μg/ml
c. 100 - 1000 μg/ml d. 1 - 10 mg/ml

1. which protein is commonly used as a standard in this assay?

a. hemoglobin b. casein
c. bovine serum albumin (bsa) d. lysozyme

1. what is the role of the standard curve in the bradford assay?

a. to measure enzyme activity
b. to calibrate the spectrophotometer
c. to relate absorbance values to known protein concentrations
d. to calculate molar extinction coefficients

1. when you do the graph of concentration of standards and absorbance, which one is the independent variable?

a. absorbance b. concentration

1. which amino acid residues contribute most to coomassie dye binding?

Explanation:

1. The Bradford assay is based on the binding of Coomassie Brilliant Blue dye to proteins.
2. The dye changes from yellow to brown when it binds to proteins.
3. The absorbance wavelength measured in the Bradford assay is 595 nm.
4. The Bradford assay is most sensitive in the protein concentration range of 1 - 100 μg/mL.
5. Bovine Serum Albumin (BSA) is commonly used as a standard in the Bradford assay.
6. The standard curve in the Bradford assay is used to relate absorbance values to known protein concentrations.
7. In the graph of concentration of standards and absorbance, concentration is the independent variable.
8. Amino acid residues like arginine have specific interactions that contribute most to Coomassie dye binding.

Answer:

1. B. Binding of Coomassie Brilliant Blue dye to proteins
2. C. Yellow → Brown
3. C. 595 nm
4. B. 1 - 100 μg/mL
5. C. Bovine Serum Albumin (BSA)
6. C. To relate absorbance values to known protein concentrations
7. b. concentration
8. Amino acid residues such as arginine contribute most to Coomassie dye binding.