BCH 2333 Lecture Notes - Lecture 9: Conformational Entropy, Molten Globule, Hydrophobic Collapse
6 Apr 2016
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Lecture 9: protein folding, quaternary structure, dna supramolecular structure. Spontaneous, the free energy has to be less than 0. The free energy is the sum of the enthalpy and the entropy of the folding. We are going from a free polypeptide and folding it: we are losing entropy but we pay for it with a large gain in enthalpy, also the hydrophobic effect pays for the loss of entropy. Giving more entropy to the water and the solvent, helps even out the loss. When we form the structures, we are increasing the number of bonds formed. Thermodynamics only tells us if it is favourable and in which direction. In the body it takes approx a second for an unfolded protein to fold back. Phi-psi has 3 preferred states (180, +60, -60). All the things that apply to the small molecules have to be maintained in the protein structure. There are about 3 conformations per residue.
