One way to determine the concentration of protein in a solution is to perform a "protein assay". There are several assay kits on the market that one can use, but they all rely on the common paradigm that the aromatic amino acid residues of a protein combine with the reagents from the protein assay kit to form a colored solution within 30 minutes. Using a spectrophotometer, one compares the intensity of the color of one's unknown protein solution with the intensities of color of the standards of known concentrations. Interestingly enough, you have a solution containing an unknown concentration of a polypeptide with the sequence "MetCysAlaArgLysLeuThrGlnVal". You perform the protein assay and no color forms. You wait and wait and still no color forms. Color does not form even after several hours because.... (Points: 4)

Question

One way to determine the concentration of protein in a solution is to perform a "protein assay". There are several assay kits on the market that one can use, but they all rely on the common paradigm that the aromatic amino acid residues of a protein combine with the reagents from the protein assay kit to form a colored solution within 30 minutes. Using a spectrophotometer, one compares the intensity of the color of one's unknown protein solution with the intensities of color of the standards of known concentrations. Interestingly enough, you have a solution containing an unknown concentration of a polypeptide with the sequence "MetCysAlaArgLysLeuThrGlnVal". You perform the protein assay and no color forms. You wait and wait and still no color forms. Color does not form even after several hours because.... (Points: 4)

a. The peptide is too small to cause a color reaction
b. There are no amino acids with aromatic rings in their structure
c. You forgot to turn on the spectrophotometer
d. Your standard curve had a "R" value of 0.899

a

Answer 1

b. There are no amino acids with aromatic rings in their structure

Answer 2

The correct answer to this question is:

b. There are no amino acids with aromatic rings in their structure.

To determine the concentration of protein in a solution, protein assays rely on the reaction between aromatic amino acid residues and reagents from the assay kit. Aromatic amino acids, such as phenylalanine, tyrosine, and tryptophan, have aromatic rings in their structures, and it is these aromatic rings that react with the reagents to form a colored solution.

In the given polypeptide sequence "MetCysAlaArgLysLeuThrGlnVal," there are no amino acids with aromatic rings. Therefore, there are no aromatic amino acid residues for the reagents of the protein assay kit to react with. As a result, no color forms in the solution after waiting for several hours.

It is important to understand the components of the protein assay and the properties of the polypeptide sequence in order to correctly determine why the color did not form in this specific scenario.

Answer 3

The correct option is:

a. The peptide is too small to cause a color reaction.

In this case, since no color forms after several hours, it suggests that the peptide is too small to cause a color reaction. Most protein assay kits rely on the interaction between aromatic amino acid residues and the reagents in the kit to produce a color change. Since the peptide sequence "MetCysAlaArgLysLeuThrGlnVal" does not contain any aromatic amino acid residues (such as phenylalanine, tyrosine, or tryptophan), it is unable to undergo the required reaction to produce color.