proteins

• Chirality


  Different geometry for amino acids
• Levorotatory


  amino group on left
• Primary Structure


  Sequence of amino acids from N-terminal to C-terminal
• Secondary Structure


  Conformations of amino acids with a particular shape of backbone
• Tertiary Structure


  3D shape of many secondaries
• Quaternary Structure


  3D arrangement of more polypeptide chains
• Covalent Bonds


  form disulphide between cysteine
• Hydrogen bonds


  polar side chains
• Salt Bridges


  electrostatic attraction, from cation to anion
• Hydrophobic interactions


  non-polar side chains interacting (dispersion forces)
• Beta Saddle and Barrel

  Tertiary Structure
• Fibrous proteins


  simple structures eg: collagen
• Globular proteins


  complex structures eg: hemoglobin
• Membrane proteins


  Intrinsic (permanently bound) and Extrinsic (mobile, not critical for function)
• What are the functions of proteins?

  1. Structure (collagen)

  2. Catalysts (kinase)

  3. Movement (myosin)

  4. Transport (hemoglobin)

  5. Signalling (insulin)

  6. Protection (fibrinogen)

  7. Storage (casein)

  8. Regulation (transciption factors)
• Protein folding (spontaneous)


  reorganize themselves with dispersion forces
• Protein folding (Assisting)


  Chaperons fold into native conformation
• Protein folding (denaturation)


  destroying conformation refer to agents
• Denaturing agents


  1. Heat

  2. 6M aqueous urea

  3. Surface-active agents

  4. Reducing agents

  5. Heavy metal ions

  6. Alcohol

  7. Extreme pH