Final answer:
The stock solution used to generate the standard curve for the Coomassie colorimetric assay is typically a known concentration of bovine serum albumin (BSA). This allows the determination of protein concentration in the sample being tested through a color change measured by absorbance.
Step-by-step explanation:
The stock solution used to generate the standard curve for the Coomassie colorimetric assay is typically a solution of bovine serum albumin (BSA), which serves as a protein standard. The established concentrations of BSA are used to produce a color change upon the addition of the Coomassie reagent—often Coomassie Brilliant Blue G-250. This change is measured by its absorbance at a specific wavelength, allowing the generation of a standard curve that can be used to determine the concentration of proteins in the sample being tested.
During the assay, known amounts of the protein standard are added to separate cuvettes containing the assay buffer and the Coomassie dye reagent. The resultant color change is measured with a spectrophotometer, typically at 595 nm for the Coomassie Blue assay. The intensity of the color, which corresponds to the absorbance, indicates the amount of protein present. The standard curve is then constructed by plotting the known concentrations of BSA against their corresponding absorbance readings, allowing for the interpolation of unknown protein concentrations in test samples.