General Properties of Proteins

• Describe the general structure of an Amino Acid

  COOH = Carboxyl Group

  R = Variable Group

  H2N = Amine Group
• Describe how Amino Acids join together

  • Condensation Reaction
  • Removing a water molecule
  • Between COOH group of one and NH2 group of another
  • Forming a peptide bond
• Describe the Primary Structure of a Protein

  Sequence of amino acids in a polypeptide chain, joined by peptide bonds
• Describe the Secondary Structure of a protein

  • Folding of polypeptide chains (e.g. Alpha Helix/Beta pleated sheets)
  • Due to hydrogen bonds forming between amino acids
  • Between the NH and C=O
• Describe the Tertiary Structure of a Protein

  • 3D folding of polypeptide chain
  • R groups interact
  • Forming Hydrogen Bonds, Ionic Bonds and Disulphide Bridges
• Describe the Quaternary Structure of a protein

  • More than one polypeptide chain
  • Formed by interactions between polypeptides (H-bonds, ionic bonds, disulphide bonds)
• Describe the test for Proteins

  1. Add biuret reagent
  2. Positive result = Blue to Lilac/Purple (negative stays blue) - Indicates presence of peptide bonds