title: The achiral tetrapeptide Z-Aib-Aib-Aib-Gly-OtBu.
abstract: The title achiral peptide N-benzyloxycarbonyl-α-aminoisobutyryl-α-aminoisobutyryl-α-aminoisobutyrylglycine tert-butyl ester or Z-Aib-Aib-Aib-Gly-OtBu (Aib is α-aminoisobutyric acid, Z is benzyloxycarbonyl, Gly is glycine and OtBu indicates the tert-butyl ester), C26H40N4O7, is partly hydrated (0.075H2O) and has two different conformations which together constitute the asymmetric unit. Both molecules form incipient 310-helices. They differ in the relative orientation of the N-terminal protection group and at the C-terminus. There are two 4→1 intramolecular hydrogen bonds.
authors.affiliation: IMBB/FORTH, 70013 Iraklion Crete, Greece.
authors.forename: Renate
authors.initials: R
authors.lastname: Gessmann
authors.affiliation: Department of Food Sciences, Interdisciplinary Research Centre, Justus-Liebig-University of Giessen, 35392 Giessen, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Brückner
authors.affiliation: IMBB/FORTH, 70013 Iraklion Crete, Greece.
authors.forename: Kyriacos
authors.initials: K
authors.lastname: Petratos
mesh_terms: D000621:Aminoisobutyric Acids / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008968:Molecular Conformation; D009842:Oligopeptides / Q000737:chemistry*
chemical_list: D000621:Aminoisobutyric Acids; C000596811:N-benzyloxycarbonyl-alpha-aminoisobutyryl-alpha-aminoisobutyryl-alpha-aminoisobutyrylglycine tert-butyl ester; D009842:Oligopeptides
keywords: 310-helices; Z-Aib-Aib-Aib-Gly-OtBu; achiral peptides; crystal structure; hydrogen bonding; peptaibol antibiotic peptides; tetrapeptides; α-aminoisobutyric acid