Question

7. Absorbance at 280 nm exhibited by protein is due to:
(A) aliphatic amino acids
(B) all amino acids
(C) non-polar amino acids
(D) aromatic amino acids​

Answer 1

Answer:d, aromatic amino acids

Explanation:

Due to the presence of tyrosine and tryptophan, proteins and peptides containing these aromatic amino acids absorb UV light at a wavelength of 280 nm

Answer 2

Absorbance at 280nm is exhibited by proteins due to aromatic amino acids. (Option D)

• Estimation and sequencing of protein in a sample can be done by various methods. One of the most convenient and sensitive method is by measuring its absorbance at a particular wavelength using a colorimeter.
• The presence of aromatic amino acids such as tryptophan and tyrosine gives colour to the sample and the concentration of protein corresponds with the value of absorbance.
• These amino acids form complexes with the reagents added to the sample and give characteristic colour. Some common reagents used are- Folin-Ciocalteu and Biuret reagent.