Question

The decreasing order of the numerical values of Molar Extinction Coefficient of following amino acids at 280 nm is:
(A). Cysteine
(B). Phenylalanine
(C). Tyrosine
(D). Tryptophan
Choose the correct answer from the options given below:

• A. (D), (C), (A), (B).
• B. (B), (C), (D), (A).
• C. (C), (D), (B), (A).
• D. (D), (B), (C), (A).

Hint:

Remember the general sequence for UV absorption of amino acids at 280 nm: \(\text{Trp} > \text{Tyr} > \text{Cys (disulfide)} > \text{Phe}\).
Phenylalanine has negligible absorption at this wavelength because its peak absorption occurs at 257 nm.

Answer 1

The Correct Option is A