title: Hippuryl-L-histidyl-L-leucine, a substrate for angiotensin converting enzyme.
abstract: The tripeptide crystallizes as a zwitterion with a protonated histidyl ring and the C-terminus ionized and with five water molecules of hydration (C21H27N5O5(.5)H2O). The tripeptide adopts an all trans extended conformation with the histidine and phenyl rings parallel to one another. The C-terminus coils into a helical conformation. An intramolecular hydrogen bond between the C-terminus and the N delta atom of the histidine ring stabilizes the helical conformation. The principal torsion angles are phi 1 = -67.7 (8), psi 1 = 140.8 (5), omega 1 = 171.0 (6), phi 2 = -156.5 (5), psi 2 = 162.7 (5), omega 2 = 175.0 (5), phi 3 = -96.4 (6), psi T1 = 14.5 (8) and psi T2 = -164.6 (6) degrees [IUPAC-IUB Commission on Biochemical Nomenclature (1970). J. Mol. Biol. 52, 1-17]. The tripeptides are linked in infinite chains through a short intermolecular hydrogen bond between the C-terminal carboxylate group and the protonated histidy1 N epsilone atom.
authors.affiliation: Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Vrielink
authors.forename: A
authors.initials: A
authors.lastname: Obel-Jorgensen
authors.forename: P W
authors.initials: PW
authors.lastname: Codding
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry* / Q000378:metabolism*; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D009842:Oligopeptides; C010980:hippuryl-histidyl-leucine; D007703:Peptidyl-Dipeptidase A