R. Bosch, G. Jung, H. Schmitt
Jun 1, 1985
Citations
0
Influential Citations
52
Citations
Journal
Biopolymers
Abstract
Boc‐L‐Leu‐Aib‐Pro‐Val‐Aib‐Aib‐Glu(OBzl)‐Gln‐Phl (Boc = t‐butyloxycarbonyl, Aib = α‐aminoisobutyric acid, Bzl = benzyl, Phl = phenylalaninol), C59H90N10O14, the protected C‐terminal nonapeptide with the sequence 12–20 of alamethicin, crystallizes in the orthorhombic space group P212121 with a = 15.666, b = 16.192, c = 26.876 Å, and Z = 4. The molecular conformation is right‐handed helical with three α‐(5 → 1 hydrogen bonds) and three β‐turns (4 → 1 hydrogen bonds). All but two of the hydrogen bonds are significantly longer than the usual value and show bifurcation to some extent. The α/3 10r ‐helical nonapeptide molecules are arranged head‐to‐tail along the a direction. The resulting linear antiparallel chains are linked by a weak intermolecular hydrogen bridge, thus forming a two‐dimensional layer structure in the ab plane. The conformation of this nonapeptide is almost identical with that of the corresponding C‐terminal part found by x‐ray crystallography of the eicosapeptide alamethicin.