2 - COLOR TESTS FOR PROTEINS

Question 1

used in the identification of proteins

Answer 1

Biuret’s Test

Question 1

Biuret’s Test

The peptide bonds in proteins react with cupric ion in alkaline medium to form

Answer 1

violet-colored complex compound

Question 2

Ninhydrin reacts with alpha amino groups of proteins forming colored complex compound.

Answer 2

Ninhydrin Test

Question 3

positive result for ninhydrin test

Answer 3

purple-colored complex

Question 4

specific to phenol-containing amino acid Tyrosine

Answer 4

Millon’s test

Question 5

made by dissolving Mercury in concentrated Nitric acid (HNO3) and diluting with water

Answer 5

Millon’s reagent

Question 6

tyrosine reacts with Millon’s reagent to produce a

Answer 6

brick-red product

Question 7

specific to the indole group of Tryptophan

Answer 7

Hopkin’s Cole test

Question 8

Tryptophan reacts with Glyoxylic acid to produce a

Answer 8

purple-colored product

Question 9

specific for Cysteine

Answer 9

Reduced Sulfur test

Question 10

When a protein is boiled with strong base, organic sulfur is converted to sulfide. The sulfide then reacts with Lead acetate (Pb(CH3COO)2) to form

Answer 10

black Lead sulfide (PbS) precipitate

Question 11

specific to the guanidine group of Arginine

Answer 11

Sakaguchi test

Question 12

Arginine reacts with alpha-naphthol to produce a

Answer 12

red-colored product

Question 13

specific to the Benzene ring of Tyrosine and Tryptophan

Answer 13

Xanthoproteic test

Question 14

The aromatic group can undergo nitration with nitric acid to produce

Answer 14

dark yellow or orange colored solution

Question 15

specific for Cysteine

Answer 15

Nitroprusside test

Question 16

Cysteine reacts with Nitroprusside to produce a

Answer 16

red complex