PROTEINS MELT WHEN YOU HEAT THEM UP...AND WHEN YOU COOL THEM DOWN?

  1. It's true!
  2. And it's likely because of something called the hydrophobic effect
  3. The hydrophobic effect is the tendency for non-polar substances to group together and exclude water, like how oil forms droplets and groups together in water
  4. When proteins heat up they gain enough energy to overcome the hydrophobic effect and unfold
    Entropy, or disorder, increases, and if you're familiar with thermodynamics you know that this is favorable.
  5. In the cold something similar happens, only it isn't disorder that drives the unfolding, it's heat
  6. So wait, HEAT is released during COLD denaturatuon?
  7. Yes, it is! Because the hydrophobic effect becomes less in the cold
  8. Water dissolving the protein becomes more rigid and structured in the cold
    Picture an ice crystal as compared to disordered water molecules at room temperature
  9. That means the protein chain is more free to interact with the ordered water, feeling the hydrophobic effect much less
    The water is too busy interacting with other waters, and it won't interact with the protein as much. This means the hydrophobic effect is less.
  10. Interacting with the ordered water lattice releases heat, just like the formation of chemical bonds
  11. And BOOM, the protein interacts more with the water than itself, and it unfolds
  12. So proteins melt in the heat because of disorder, and they melt in the cold because of heat. Wild.