title: Unexpected stability of the urea cis-trans isomer in urea-containing model pseudopeptides.
abstract: In contrast to the situation observed in the crystal state, the urea moiety in N-Boc-N'-carbamoyl-gem-diaminoalkyl derivatives (single-residue ureidopeptides) 1-4 exclusively assumes a cis-trans conformation in solution. When R(3) = H, the resulting structure can be further stabilized by an intramolecular hydrogen bond that closes an eight-membered pseudocycle. The root-mean-square deviation calculated for heavy atoms between a peptide gamma-turn and the folded conformation that we propose to call urea turn is 0.60 A. [structure: see text]
authors.affiliation: Immunologie et Chimie Thérapeutiques, UPR CNRS 9021, IBMC, 15, rue Descartes, F-67084 Strasbourg, France.
authors.forename: V
authors.initials: V
authors.lastname: Semetey
authors.forename: C
authors.initials: C
authors.lastname: Hemmerlin
authors.forename: C
authors.initials: C
authors.lastname: Didierjean
authors.forename: A P
authors.initials: AP
authors.lastname: Schaffner
authors.forename: A G
authors.initials: AG
authors.lastname: Giner
authors.forename: A
authors.initials: A
authors.lastname: Aubry
authors.forename: J P
authors.initials: JP
authors.lastname: Briand
authors.forename: M
authors.initials: M
authors.lastname: Marraud
authors.forename: G
authors.initials: G
authors.lastname: Guichard
mesh_terms: D007536:Isomerism; D008956:Models, Chemical; D010455:Peptides / Q000737:chemistry*; D014508:Urea / Q000737:chemistry*
chemical_list: D010455:Peptides; D014508:Urea