NEET PG Medical – 2020 – Question -31
Addition of which Amino Acid will increase UV absorption
a) Tryptophan
b) Leucine
c) Proline
d) Arginine
Correct Answer – A
Ans: A. Tryptophan
Amino Acid Absorb UV Light
Amino Acids that absorb 250-290 nm (Maximum at 280 nm) UV light are tryptophan, phenylalanine, tyrosine.
The maximum absorption of UV light is by tryptophan.
As it absorbs ultraviolet light about ten times more efficiently than phenylalanine or tyrosine, tryptophan makes the major contribution to the ability of most proteins to absorb light in the region of 280 nm.
Tryptophan and tyrosine absorb UV at approximately 280 nrn.
UV absorption spectroscopy is utilized to measure protein concentration. The absorption spectrum of a protein in the UV
wavelength range is the result of absorption of light by the aromatic amino acids (250-320 nm), the disulfide bonds (250-300 nm) and the carbonyl group of the peptide bond (190-210).
RememberÂ
Aromatic Amino Acids absorb UV Lights
Amino acids are colourless because they do not absorb visible light.
Ref-Rebecca james-self assessment and review of biochemistry, 3rd edn, Chemistry, and Metabolism of Amino Acids, Pg
