BIOMOLECULES AND ENZYMES

Detailed explanation-1: -All aryl amino acids give xanthoproteic test except phenylalanine, this is so because the benzene group present in phenylalanine is very stable and it does not react with nitric acid in normal conditions. Therefore, all amino acids do not give a positive xanthoproteic test.

Detailed explanation-2: -Xanthoproteic test is used to detect amino acids containing an aromatic nucleus (tyrosine, tryptophan and phenylalanine) in a protein solution which gives yellow color nitro derivatives on heating with conc. HNO3. The aromatic benzene ring undergoes nitration to give yellow colored product.

Detailed explanation-3: -The Xanthoproteic test uses a nitration reaction to determine the presence of proteins in a solution. When the sample is treated with a hot, concentrated nitric acid it reacts with aromatic amino acids such as phenylalanine, tyrosine and tryptophan and forms a yellow colored product known as Xantho protein.

Detailed explanation-4: -Isatin test is a biochemical test for the detection of amino acids like proline and hydroxyproline. The test is a specific test for specific amino acids that produces a colored addition product (also called adduct) with the Isatin reagent.

Detailed explanation-5: -Xanthoproteic Test When this yellow solution is treated with a strong base (such as NaOH), it turns orange. Since most proteins contain one or both of these amino acids, most proteins will show a positive reaction in this test.