Water

Lets start with an answer: "The entropy of water". But what was the question again?

Obviously nearly all questions can be answered with "The entropy of water", but often one needs a bit of reasoning to get there. Here we will look at waters in proteins. Lets start with a molecule that has water as its hobby: aquaporin.

Figure 41. Aquaporin. A good starting point for an aquaporin study can be found in Denmark . And Bert de Groot in Goettingen made a highly illustrative series of movies . If it takes too long to download them, feel free to use the local copy.

Aquaporin makes a nice story. A story where bioinformatics plays a major role. But there are more roles for water. We know that the main 'function' of water is providing the entropy when a protein folds . But what other functions does water have? Think of a few roles for water molecules when studying proteins in general.

Question 32:

• Where in the body do aquaporins fulfill what function(s)?
• What is the helix dipole moment, how is it formed, and in which direction does it point?
• What is the most striking aspect of this structure?
• What can you say about the structure - function relation?
• How come water - specific aquaporins only let water through?
• Think of four very different functions for water when studying proteins in general.