BIOMOLECULES AND ENZYMES

Detailed explanation-1: -The reagent is made by dissolving metallic mercury in nitric acid and diluting with water, forming mercuric nitrate (Hg[NO3]2). In the test, the phenol group in the side chain of tyrosine gets nitrated, and that product then complexes with Hg(I) or Hg(II) ions to give a red colored precipitate.

Detailed explanation-2: -b) Millon’s Test: Millon’s reagent is concentrated HNO3, in which mercury is dissolved. As a result of the reaction a red precipitate or a red solution is considered as positive test. A yellow precipitate of HgO is NOT a positive reaction but usually indicates that the solution is too alkaline.

Detailed explanation-3: -Principle of Millon’s test: Compounds containing hydroxybenzene radical react with Millon’s reagent to form red complexes. The only amino acid having hydroxybenzene ring is tyrosine. Thus, this test is specific for the amino acid tyrosine and the protein containing this amino acid.

Detailed explanation-4: -Phenolic group of tyrosine of proteins reacts with mercuric sulfate in the presence of sodium nitrite and sulfuric acid to give red color. Millon’s test is given by proteins containing phenolic amino acids.

Detailed explanation-5: -Millon’s test is specific test for identification of tyrosine. Tyrosine containing protein when reacts with acidified mercuric sulphate solutions gives yellow precipitate of mercury protein complex.