Which of the following statements about the α-helix is TRUE? There are 3 amino acids per helical turn. It is composed of 2 polypeptides that come together to form a left-handed helix. The structure is stabilized by ionic bonds between the nth amino acid residue and (n+4)th amino acid residue. A polylysine chain could form into an α-helix at pH 12.8. None of the above