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Unusual conformational preferences of β‐alanine containing cyclic peptides. VII
Author(s) -
Lombardi Angela,
Saviano Michele,
Nastri Flavia,
Maglio Ornella,
Mazzeo Marco,
Pedone Carlo,
Isernia Carla,
Pavone Vincenzo
Publication year - 1996
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.360380602
Subject(s) - chemistry , intramolecular force , pentapeptide repeat , stereochemistry , cyclic peptide , alanine , residue (chemistry) , hydrogen bond , orthorhombic crystal system , crystal structure , ring (chemistry) , molecule , peptide , crystallography , turn (biochemistry) , amino acid , organic chemistry , biochemistry
In the present paper we describe the synthesis, purification, and single crystal x‐ray analysis of the cyclic pentapeptide cyclo‐(Pro‐Phe‐Phe‐β‐Ala‐β‐Ala). This compound crystallizes in the orthorhombic space group P2 1 2 1 2 1 from methanol and adopts in the solid state an unusual conformation characterized by a cis β‐Ala 5 ‐Pro 1 peptide bond and by an intramolecular hydrogen bond stabilizing a C 11 ‐ and a C 12 ‐ring structure. The C 11 , structure contains the Phe 3 and the β‐Ala 4 at the corner position of the turn; it is the first observation of a type II β‐turn enlargement due to the insertion of an extra methylene group of the β‐alanine residue. The rest of the molecule participates in a newly characterized C 12 ‐ring structure, which incorporates a β‐Ala residue at position i of the turn. © 1996 John Wiley & Sons, Inc.