Aromatic amino acids absorb light in the near-ultraviolet region of the electrom

Question

Aromatic amino acids absorb light in the near-ultraviolet region of the electromagnetic spectrum. Which of the following statements about absorption of proteins are true? 1. The absorption of light at 280 nm is often used for the detection and/or quantification of proteins. 2. Phenylalanine does not absorb at 280 nm, and it absorbs only weakly at 258 nm. 3. Amino acids absorb as strongly as nucleic acids 4. Tryptophan and tyrosine account for most of the UV absorbance by proteins in the region around 280 nm. View Available Hint(s) 2, 3, and 4 2 and 4 1 and 4 1,2, and 4

Explanation / Answer

ANSWER) D- 1 ,2 and 4

The absorption of light at 280nm is often used for detection of proteins. Phenylalanine, Tryptophan and tyrosine are aromatic amino acids which absorb UV spectrum.

Nucleic acids absorb in region of 240 to 275nm, UV at 260 nm is generally taken for nucleic acids.

A ratio of 260/280 is taken to determine the purity of sample.

Pure DNA- 1.8

Pure RNA – 2

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