Proteins

• Proteins

  Complex macromolecule made up of amino acids produced by all living cells
• Proteins

  • Different size, shape, charges
  • Different functions
• Amino acids

  Composed of 20 amino acids varying in numbers and sequences
• Amino acids

  Contain both a CARBOXYLIC GROUP and an amino group and a side chain (R group)
• Building block of proteins

  Amino acids
• All proteins are composed of C-H-O-N and some of proteins contain Sulfur
• Biuret test

  General test for proteins<|>Gives positive result for compounds that contain peptide linkages = purple or violet color<|>Principle: Cupric ions in an alkaline medium form a violet colored complex with peptide bond nitrogen of peptides and Proteins
• Biuret test

  • Reagents: 10% NaOH, Copper sulfate
  • Result: violet or purple color (+)
• Hopkins-Cole test


  Principle: The indole ring of tryptophan combines with aldehydes, e.g formaldehyde in the presence of conc. Sulfuric acid to form a violet-colored compound
• Hopkins-Cole test


  • Reagents: Hopkin's Cole Rgt: Formaldehyde + mercuric sulfate [mild oxidation of indole group of tryptophan] + sulfuric acid, Sulfuric acid
  • Result: It forms a separate layer and a deep violet or purple ring [TRYPTOPHAN] forms at the junction of the two layers
• Solubility


  The maximum amount of solute that can be dissolved in a solvent at a specific temperature and pressure