The pi-helix is a rare secondary structural element in proteins that resembles an alpha helix but has slightly different properties. Notably, hydrogen bonds within a pi-helix display a repeating pattern in which the backbone C=O of residue i hydrogen bonds to the backbone HN of residue i+5. Based on this information, which of the following are true? Select all that apply. O The hydrogen bonding distance between C=O and NH groups remains unchanged between pi-helices and alpha-helices The torsion angles of amino acids found in pi-helices are the same as those found in alpha-helices Pi-helices have a smaller rise per residue compared to alpha- helices Pi-helices have fewer residues per turn compared to alpha-helices Pi-helices have more residues per trn compared to alpha-helices Pi-helices are left handed