Premium
Solution conformations of some azetidine cyclic peptides
Author(s) -
Meraldi J.P.,
Blout E. R.,
Boni R.,
Verdini A. S.
Publication year - 1978
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.1978.360171009
Subject(s) - chemistry , conformational isomerism , azetidine , ring (chemistry) , cyclic peptide , stereochemistry , crystallography , peptide , molecule , organic chemistry , biochemistry
The 1 H‐nmr spectra (270 MHz) of cyclic di‐ and tri‐ L ‐azatidine‐2‐carboxylic acid [cy‐clo( L ‐Aze) 2 and cyclo( L ‐Aze) 3 ] were determined in CDCl 3 and D 2 O and computer simulated. The spectral results were compared with those obtained with cyclo ( L ‐Pro) 2 and cyclo ( L, ‐Pro) 3 . In CDCl 3 and D 2 O solution, the four membered ring of cyclo ( L ‐Aze) 2 is puckered with the α‐proton in a pseudo‐axial position, and the ϕ angle is smaller in absolute value than −60°, as found for cyclo ( L ‐Pro) 2, . The puckering of the four‐membered ring of cyclo( L, ‐Aze) 3 in CDCl 3 has the α‐proton in a pseudo–equatorial position and ϕ angle larger in absolute value than −60°, in agreement with cyclo( L ‐Pro) 3 . In D 2 O, cyclo( L ‐Aze) 3 was found to interconvert rapidly between different conformers. In the azetidine cyclic peptides studied, the range of values found for the ϕ angles was smaller than in the related proline cyclic peptides, indicating greater rigidity in the four‐membered ring.