L13- protein folding Flashcards
What is the equation for Gibbs energy?
∆G=∆H-T∆S
For a reaction to proceed what must ∆G be?
Negative. So enthalpy decreases and entropy increases.
How can an increase in entropy be brought about?
By the displacement of water- increasing the randomness of water molecules.
When does hydrophobic collapse happen?
At the same time as formation of secondary structure.
What is the hydrophobic effect?
Non polar amino acid side chains associate with each other causing a polypeptide chain to collapse to a hydrophobic core.
What do H bonds do?
Contribute to cooperativity of folding
help stabilize secondary structures and native conformation ie tertiary and quaternary structure
Where do Van der Waals occur?
between non-polar side chains (and contribute to the stability of proteins)
Where do charge-charge interactions happen?
Between the oppositely charged side chanes in the interior of a protein - also stabilize the protein structure
What allows protein folding to happen in the crowded cell?
Molecular chaperones- by stabilising intermediates thereby minimising misfolding and aggregation.
Optimises yield of correctly folded proteins.
Which classes of chaperones fold in th cytosol?
Hsp 70- which take it as soon as it.s coming out the ribosome
Hsp 60- like a barrel around it afterwards, then lets go to correctly folded protein
What does lack of cofactors lead to?
A build up of intermediates in the folding pathway
What can misfolding lead to?
Aggregation leading to toxicity
