Question

The A260/A280 ratio method estimates protein ________________ by measuring the absorbance maximum at 280nm caused by the amino acids___________________, ___________________, and ___________________. Since _______________ also absorbs in the UV range, we can correct for this contaminate by measuring the absorbance maximum at __________ and using the following equation: _______________________________________________________ When extrapolated from a standard curve, the Bradford data indicates the amount (in _____ ) of _________ protein found in a sample. If you know the volume of sample that was added to the assay then you can calculate the protein _________________ of the sample. The coomassie blue dye in the Bradford assay specifically binds primary ¬¬__________ and _________ groups of the amino acid side groups of the proteins. The more the dye binds to the sample, the __________ the blue color will be, and the absorbance at 595¬nm will be_______________. A sample with an unusually ________ number of _______________ [give a specific example] amino acids will underestimate the total amount of protein present in the sample.

Answer 1

By way of introduction, A260/A280 ratio is use to measure Protein Contamination. This procedure was first described to measure protein purity in the presence of nucleic acids. However it is now commonly used to assess protein contamination of DNA. The method to determine the concentration of protein contamination by using A260/280 ratio method is well explained below by filling in the missing words.

Step-by-step explanation:

The A260/A280 ratio method estimates protein __purity___ by measuring the absorbance maximum at 280nm caused by the amino acids__cytosine___, ____Adenine____, and ___Guanine_________ Since ___Spectrophotometer____ also absorbs in the UV range, we can correct for this contaminate by measuring the absorbance maximum at ____260nm______ and using the following equation: Concentration (µg/ml) = (A260 reading – A320 reading) × dilution factor × 50µg/ml___ When extrapolated from a standard curve, the Bradford data indicates the amount (in _ug__ ) of __unknown ___ protein found in a sample. If you know the volume of sample that was added to the assay then you can calculate the protein ____concentration ___ of the sample. The coomassie blue dye in the Bradford assay specifically binds primary ¬¬___sulfonic___ and __positive amines__ groups of the amino acid side groups of the proteins. The more the dye binds to the sample, the _anionic_ the blue color will be, and the absorbance at 595¬nm will be_shifted Amax___. A sample with an unusually __protein___ number of ___280nm of Tyrosine __ [give a specific example] amino acids will underestimate the total amount of protein present in the sample.