Diffraction Studies of Model and Natural Helical Peptides

摘要: The discovery of naturally occurring peptides that form voltage-gated ion channels in bilayer membranes has provided an impetus for the study structural characteristics this class (Mueller and Rudin, 1968; Mathew Balaram, 1983). relative difficulty obtaining crystals natural determining their structure led to synthesis many apolar are fragments or analogs peptides. contain a number a-aminoisobutyric acid (Aib) residues, (Fig. 16.1) which have proven be strong helix formers (Marshall Bosshard, 1972; Burgess Leach, 1973; 1984). A review crystal structures small linear peptides, containing up five residues including at least one Aib residue, demonstrated 28 out 29 incipient 310-helix (Toniolo et al., Thirty-three 7–16 residue more shown completely helical conformations with 310-helix, α-helix, mixed 310/ depending mostly upon length peptide (Karle 1990).