Question

Which of the following tests are used for the detection of protein?
A. Biuret test
B. Iodine test
C. Protein test
D. Glucose test

Answer 1

Hint: Proteins are macromolecular structures that are made up of many amino acids joined together in a chain which is called the peptide chain and is connected by peptide bonds. After the peptide chain is formed it undergoes certain modifications to produce the final protein molecule.

Complete Answer:
- Proteins are of importance because they serve as essential nutrients in the body serving as components for many biological processes. Proteins provide 4kcal energy per gram which is the same as that of carbohydrates. Protein detection studies are carried out for clinical diagnosis, treatment as well as for biological research.
- The most widely known test for the detection of protein is biuret test. This test detects the presence of peptide bonds. Biuret test is carried out using biuret reagent which is made up of sodium hydroxide, hydrated copper sulphate and potassium sodium tartrate.
- Potassium sodium tartrate stabilizes the cupric ions which then interact with the nitrogen atoms of the peptide bond, this in turn leads to displacement of the peptide hydrogen atoms. This is followed by the reduction of the cupric ions leading to the formation of the characteristic blueish purple color which is indicative of a positive test.

So the correct option is A) Biuret test.

Note: The biuret test is important in the detection of proteins because they give us an idea about the concentration of the proteins present in the sample. The protein concentration can be detected by measuring absorbance at 540nm using the Beer-Lambert Law.