Amino Acids and Protein Detection Tests

Amino Acids and Proteins

• An amino acid consists of an amino group, a carboxyl group, a hydrogen atom, and a distinctive R group bonded to a carbon atom.

Protein Detection Tests

• Color producing tests are used to detect proteins in biological mixtures.
• These tests include the Biuret, Ninhydrin, Millon's, and Hopkins - Cole tests, among others.

Biuret Test

• The Biuret test is a general test that gives a positive result with all proteins and amino acids.
• The test depends on the reaction of cupric ions (Cu+2) in an alkaline solution with peptide linkages of the protein to produce a purple color.
• Objective: detect the presence of peptides or proteins in a sample.
• Principle: Proteins and peptides form a purple color when treated with an alkaline solution of dilute copper sulfate.
• A positive test is indicated by the formation of a purple color.
• The color density is proportional to the amount of proteins present.
• Biuret reagent: alkaline copper sulfate solution.

Biuret Test Procedure

• Add 1 ml of 2% albumin (protein) to a tube.
• Add 0.5 ml of biuret reagent and mix well.
• Add 2 ml of 10% NaOH to the tube.

Amino Acids and Proteins

• An amino acid consists of an amino group, a carboxyl group, a hydrogen atom, and a distinctive R group bonded to a carbon atom.

Protein Detection Tests

• Color producing tests are used to detect proteins in biological mixtures.
• These tests include the Biuret, Ninhydrin, Millon's, and Hopkins - Cole tests, among others.

Biuret Test

• The Biuret test is a general test that gives a positive result with all proteins and amino acids.
• The test depends on the reaction of cupric ions (Cu+2) in an alkaline solution with peptide linkages of the protein to produce a purple color.
• Objective: detect the presence of peptides or proteins in a sample.
• Principle: Proteins and peptides form a purple color when treated with an alkaline solution of dilute copper sulfate.
• A positive test is indicated by the formation of a purple color.
• The color density is proportional to the amount of proteins present.
• Biuret reagent: alkaline copper sulfate solution.

Biuret Test Procedure

• Add 1 ml of 2% albumin (protein) to a tube.
• Add 0.5 ml of biuret reagent and mix well.
• Add 2 ml of 10% NaOH to the tube.