Xanthoprotein

The yellow color that appears on your skin if it comes in contact with nitric acid has quite a different explanation. Nitric acid reacts with proteins to give a yellow material called xanthoprotein. 

X. See Mole fraction X-ray diffraction, 248 Xanthoprotein, 571 Xenon tetrafluoride, 100,180... 

The xanthoprotein test. This is a characteristic reaction of proteins that contain phenyl rings... 

The yellow stains on the skin caused by nitric acid are the result of the xanthoprotein reaction. 

The xanthoprotein test. (Perform the experiment under the hood.) Place 15 drops of each of the following solutions in five clean, labeled test tubes ... 

Which of these metal ions gives a positive test with casein in milk Xanthoprotein test... 

Xanthoprotein reactions are given by proteins with aromatic side groups On addition of nitric acid, the product turns yellow and, after further addition of ammonia, orange. The Millon reaction is specific for tyrosine On boiling, e.g., egg-white solution with a solution of mercury in nitric-acid containing nitrous acid, a red-brown precipitate is formed. 

Xanthoprotein reaction a qualitative test for protein, using concentrated nitric acid. The resulting yellow color is due to nitration of aromatic amino acid residues... 

Xanthoprotein Test.—Add 5 drops of concentrated nitric acid to about 3-5 ml. of protein solution. A precipitate forms if higher proteins be present (Heller s test). Heat the mixture. A yellow colour develops if the test be positive. Cool, and make alkahne with ammonium hydroxide. The colour deepens to orange. 

Gelatin is the commonest protein that does not give the xanthoprotein test owing to its lack of the necessary amino acids. 

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