For more, see Proline on wikipedia.
- This closed cycle enables only a little freedom of movement and usually bends the backbone. For example, it can often be found in a short strand that links two strands of a sheet.
- The cycle formed forbids any hydrogen bond of the backbone: thus it is almost never found within helixes or sheets, but is often found in the first turn of a helix.
- This amino acid is weakly hydrophobic, but is often found on the "water side" of the molecule.