10.1021/ja0607133.s001
Rebecca A. Jockusch
Rebecca A.
Jockusch
Francis O. Talbot
Francis O.
Talbot
Paul S. Rogers
Paul S.
Rogers
Michela I. Simone
Michela I.
Simone
George W. J. Fleet
George
W. J. Fleet
John P. Simons
John P.
Simons
Carbohydrate Amino Acids: The Intrinsic Conformational
Preference for a β-Turn-Type Structure in a Carbopeptoid
Building Block
American Chemical Society
2006
conformer
alternative structures
carbopeptoid units form
C 10
sugar ring
NH
DFT
ab initio calculations
carbopeptoid dimer unit
Intrinsic Conformational Preference
amide
preference
gas phase
2006-12-27 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Carbohydrate_Amino_Acids_The_Intrinsic_Conformational_Preference_for_a_Turn_Type_Structure_in_a_Carbopeptoid_Building_Block/3037561
Infrared ion-dip spectroscopy coupled with DFT and ab initio calculations are used to establish
the intrinsic conformational preference of the basic structural unit of a peptide mimic, a <i>cis</i>-tetrahydrofuran-based “carbopeptoid” (amide−sugar−amide), isolated at low temperature in the gas phase. The carbopeptoid
units form a β-turn-type structure, stabilized by an intramolecular NH → OC hydrogen bond across the
sugar ring, thus forming a 10-membered, C<sub>10</sub> turn. Despite the clear preference for C<sub>10</sub> β-turn structures in
the basic unit, however, the presence of multiple hydrogen-bond donating and accepting groups also
generates a rich conformational landscape, and alternative structures may be populated in related molecules.
Calculations on an extended, carbopeptoid dimer unit, which includes an alternating amide−sugar−amide−sugar−amide chain, identify conformers exhibiting alternative hydrogen-bonding arrangements that are
somewhat more stable than the lowest-energy double β-turn forming conformer.