Structural Properties and Stereochemically Distinct Folding Preferences of 4,5-cis and trans-Methano-L-Proline Oligomers: The Shortest Crystalline PPII-Type Helical Proline-Derived Tetramer.
The synthesis, structural properties, and folding patterns of a series of L-proline methanologues represented by cis- and trans-4,5-methano-L-proline amides and their oligomers are reported as revealed by X-ray crystallography, circular dichroism measurements, and DFT calculations. We disclose the first example of a crystalline tetrameric proline congener to exhibit a polyproline II helical conformation. Experimental evidence of PPII-type helical arrangement (both in solution and in the solid state) of cis-4,5-methano-L-proline oligomers is supported by theoretical calculations reflecting the extent of n→π* stabilization of the trans-amide conformation.
Department of Chemistry, Université de Montréal, Station Centre-Ville, C.P. 6128, Montreal, QC, H3C 3J7 (Canada).|Faculty of Pharmacy, Laboratory of Pharmaceutical Chemistry, Université Libre de Bruxelles, Campus Plaine CP205/5, Université Libre de Bruxelles, Bd du Triomphe, 1050 Brussels (Belgium).
Gilles
G
Berger
Department of Chemistry, Université de Montréal, Station Centre-Ville, C.P. 6128, Montreal, QC, H3C 3J7 (Canada).
Miguel
M
Vilchis-Reyes
Department of Chemistry, Université de Montréal, Station Centre-Ville, C.P. 6128, Montreal, QC, H3C 3J7 (Canada). stephen.hanessian@umontreal.ca.
Stephen
S
Hanessian
D018360:Crystallography, X-Ray; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D011392:Proline / Q000031:analogs & derivatives / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D011789:Quantum Theory; D013237:Stereoisomerism
D010455:Peptides; C011083:polyproline; D011392:Proline
circular dichroism; methanoproline; natural bond orbitals; polyproline