Workshop #3 Solutions

3B. Looking at the diagram on the back, one would assume that glutamic acid would be more soluble in water than alanine (because of polarity or the fact that it says "hydrophillic/phobic" in the tables. Note: Olek says those are words to avoid...). After careful consideration, however, we can see that alanine is more soluble in water for a rather simple reason- it's size. Glutamic acid is bigger, so it would have to break way more water-water bonds to dissolve in water than alanine would. This means dissolving alanine in water is more favorable in terms of deltaG because it takes more energy to break the water bonds for glutamic acid. 

3C.  1) There are MANY configurations/conformations/tertiary structures (all the same thing). But only the most stable of the structures act as an enzyme. (Derek aside: what are other random things that can affect the structures? temperature, charges, pH).

2) We would have to know BDEs and relative number of conformations in order to predict the largest ratio.

3D. Sucrose (models on BIO 110 site)  {but is a glucose attached to a fructose}.

3E. There are many different conformations for the enzyme, sucrase. The enzymes that are the most stable tend to fit nicely around a sucrose molecule. The sucrase molecule sneaks up on the sucrose molecule and wraps itself around it. How? There are charges on both molecules that attracts them together. Sucrase essentially "pulls" on the attached glucose and fructose molecule, stretching out the bond in between them. This makes the bond weaker so a "less crazy water molecule" can hit it and possibly break it. Now, not only can the "crazier" water molecules that were able to break sucrose before, break the sucrose, but so can the "less crazy." This, in effect, increases the reaction rate of sucrose hydrolysis forming glucose and fructose.

3F. Filter! You could test different enzymes on molecules that you know the size of (and the size of what they would break up into). This way, you could filter out the broken up molecules from the not-yet-broken-up molecules. You can compare the TIME that it takes for each enzyme to break these molecules. 

3G. What you would need to know about these polypeptide chains is that they have charges going along the chain. When they roll up and configure the way that they do, the + and - charges on the chain tend to line up together (because opposites attract). These + and - charges are present on H+s and OH-s. Knowing this, you could engineer the enzyme to effectively wrap around a molecule. 

3H. Yes, it is important! Some proteins are more soluble in water than others because of their size, polarity, etc... You can make a protein relatively insoluble in water but more soluble in a lipid by make it nonpolar. Lipids are nonpolar, so they'd go together great.