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Solvent‐mediated conformational transition in β‐alanine containing cyclic peptides. VIII
Author(s) -
Lombardi Angela,
Saviano Michele,
Nastri Flavia,
Maglio Ornella,
Mazzeo Marco,
Isernia Carla,
Paolillo Livio,
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/(sici)1097-0282(199602)38:6<693::aid-bip2>3.0.co;2-q
Subject(s) - chemistry , alanine , cyclic peptide , transition (genetics) , stereochemistry , solvent , peptide , organic chemistry , biochemistry , amino acid , gene
In the present paper we describe the solution nmr structural analysis and restrained molecular dynamic simulation of the cyclic pentapeptide cyclo‐ (Pro‐Phe‐Phe‐β‐Ala‐β‐Ala). The conformational analysis carried out in CD 3 CN and dimethylsulfoxide (DMSO) solutions by nmr spectroscopy was based on interproton distances derived from rotating frame nuclear Overhauser effect spectroscopy spectra and homonuclear coupling constants. A restrained molecular dynamic simulation in vacuo was also performed to build refined molecular models. The molecule is present in both solvent systems as two slowly interconverting conformers, characterized by a cis‐trans isomerism around the β‐Ala 5 ‐Pro 1 peptide bond. In CD 3 CN solution, the conformer with a cis peptide bond is quite similar to that observed in the solid state, while the conformer containing all trans peptide bonds is characterized by an intramolecular hydrogen bond stabilizing a C 10 ‐ and a C 13 ‐ring structure. In DMSO solution, the trans isomer is partly similar to that observed in CD 3 CN solution while the cis isomer is different from that observed in the solid state. The effect of the solvent in stabilizing different conformations was also investigated in DMSO‐CD 3 CN solvent mixtures. © 1996 John Wiley & Sons, Inc.