Chapter 6, Problem 10P

Under physiological conditions, the protein hemerythrin exists as an octamer of eight chains of the kind shown in Problem 3.
a. Name two symmetries possible for this molecule
b. Which do you think is more likely? Explain.
c. For the more likely symmetry, what kinds of interactions (isologous, heterologous, or both) would you expect? Why?

3. A schematic structure of the subunit of hemerythrin (an oxygen-binding protein from invertebrate animals) is shown to the right.
a. It has been found that in some of the a-helical regions of hemerythrin, about every third or fourth amino acid residue is a hydrophobic one. Suggest a structural reason for this finding.
b. What would be the effect of a mutation that placed a proline residue at point A in the structure?