Final answer:
Protein concentration can be quantified using the Bradford assay or mass spectrometry, and protein purity can be checked using gel electrophoresis or size exclusion chromatography.
Step-by-step explanation:
Quantifying Protein Concentration and Checking Protein Purity
There are several methods to quantify protein concentration and to check protein purity. One common method to quantify protein concentration is the Bradford assay, which is a colorimetric assay that uses Coomassie Brilliant Blue dye binding to measure protein concentration. In this assay, the absorbance of the sample is measured at a particular wavelength, typically the bluer the sample, the higher the protein concentration. Another method is mass spectrometry, which can provide very accurate data regarding protein quantities, even for complex protein mixtures.
To assess the purity of proteins, gel electrophoresis such as SDS-PAGE can be used where proteins are separated based on their size. After electrophoresis, the gel is stained, and the purity can be evaluated by the pattern of bands obtained. For more detailed analysis, techniques like size exclusion chromatography (SEC) or isoelectric focusing (IEF) can be applied, which separate proteins based on their size or isoelectric point, respectively.