Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Antifreeze proteins help

  1. Dec 15, 2004 #1
    Anyone know the answer to this ridiculous problem

    Antarctic notothenioid fish avoid freezing in their perpetually icy environment because of an antifreeze protein that circulates in their blood. This evolutionary adaptation has allowed these fish to rise to dominance in the freezing southern ocean. It is said that all proteins function by binding to other molecules. To what ligand do you suppose antifreeze proteins bind to keep the fish from freezing.? Or do you think this might be an example of a protein that functions in the absence of any molecular interaction?

    Anyone have any suggestions, thanks
  2. jcsd
  3. Dec 15, 2004 #2
    I would have to guess... the ligand would be ice crystals to stop them from growing.
  4. Dec 15, 2004 #3


    User Avatar

    If there is a ligand, then I suppose it would be water. Some chemical functioning in the absence of any interaction sounds kinda fishy to me.... Pun intended. But biology isn't my thing.
    Last edited: Dec 15, 2004
  5. Dec 15, 2004 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    You are right. The protein binds to tiny ice crystal and prevent the growth of these crystals.

    But in more technical terms


    More info
  6. Dec 16, 2004 #5


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    It seems the question has already been answered. The choice of the word "ligand" seems odd in this context. I usually think of ligand as a molecule binding to a receptor, not just any molecular interaction. I wouldn't consider water to be a "ligand" in the true sense of the word.
  7. Dec 16, 2004 #6


    User Avatar
    Science Advisor

    I agree, in most cases the ligand elicits some sort of reaction in the protein it is binding to, i.e., conformational change, translocation, channel activation, etc. In this case it appears that active groups, the long chain amino acids are functionally exposed prior to exposure to ice and ready to interact with the forming edges of ice crystals, so it's not necessarily reacting but simply inhibiting.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook