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PROTEIN FOLDING

1. proteins = polypeptides folded into 3D structure due to..

   • alpha helix
   • beta-pleated sheet
   • ionic interactions
   • hydrophobic interactions
   • van der Waal forces
   • disulphide bridges

2. FUNCTIONAL STRUCTURES

   • number of functional structures = 1 (possible few variations retain protein function)
   • may be > 100,000 different proteins in an organism
   • each requiring specific folding for appropriate function
   • for many proteins functional structure = soluble non-functional structure = insoluble/aggregate

3. MECHANISMS OF FOLDING

   • normal in vivo protein folding occurs in a crowded complex environment
   • possible correct folding in vitro under appropriate conditions
   • reduced, unfolded ribonuclease A --- spontaneous ---> native (active) state ribonuclease A

4. folded protein most energetically stable

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