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The crystal and molecular structure of the α‐helical nonapeptide antibiotic leucinostatin A
Author(s) -
Cerrini S.,
Lamba D.,
Scatturin A.,
Rossi C.,
Ughetto G.
Publication year - 1989
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360280138
Subject(s) - antiparallel (mathematics) , chemistry , hydrogen bond , intramolecular force , crystallography , orthorhombic crystal system , van der waals force , crystal structure , molecule , stereochemistry , helix (gastropod) , ecology , physics , organic chemistry , quantum mechanics , snail , magnetic field , biology
The crystal and molecular structure of the nonapeptide antibiotic leucinostatin A, containing some uncommon amino acids and three Aib residues, has been determined by x‐ray diffraction analysis. The molecule crystallizes in the orthorhombic space group P2 1 2 1 2 1 , a = 10.924, b = 17.810, c = 40.50 Å, C 62 H 111 N 11 O 13 , HCl · H 2 O, Z = 4. The peptide backbone folds in a regular right‐handed α‐helix conformation, with six intramolecular i ← ( i + 4) hydrogen bonds, forming C 13 rings. The nonapeptide chain includes at the C end an unusual β‐Ala residue, which also adopts the helical structure of the other eight residues. In the crystal the helices are linked head to tail by electrostatic and hydrogen‐bond interactions, forming continuous helical rods. The crystal packing is formed by adjacent parallel and antiparallel helical rods. Between adjacent parallel helical columns there are only van der Waals contacts, while between adjacent antiparallel helical columns hydrogen‐bond interactions are formed.