Problem:

Question: Why is proline frequently encountered at the places in the myoglobin and hemoglobin molecules where the polypeptide chain turns a corner?

Pick all that apply

1. Proline fits well into a reverse turn between ?-strands.

2.Proline fits well into a reverse turn between ?-helix segments.

3.Proline, unlike the rest of the other amino acids, has a fixed angle between its ?-C-C bond and ?-C-N bonds.

4.Proline, due to its structure, cannot fit into the geometry of an ?-helix.

5.Proline, due to its structure, cannot fit into the geometry of a ?-sheet.

Any help would be greatly appreciated!