title: The influence of peptide structure on transport across Caco-2 cells.
abstract: The relationship between structure and permeability of peptides across epithelial cells was studied. Using confluent monolayers of Caco-2 cells as a model of the intestinal epithelium, permeability coefficients were obtained from the steady-state flux of a series of neutral and zwitterionic peptides prepared from D-phenylalanine and glycine. Although these peptides ranged in lipophilicity (log octanol/water partition coefficient) from -2.2 to +2.8, no correlation was found between the observed flux and the apparent lipophilicity. However, a strong correlation was found for the flux of the neutral series and the total number of hydrogen bonds the peptide could potentially make with water. These results suggest that a major impediment to peptide passive absorption is the energy required to break water-peptide hydrogen bonds in order for the solute to enter the cell membrane. This energy appears not to be offset by the favorable introduction of lipophilic side chains in the amino acid residues.
authors.affiliation: Drug Delivery Systems Research, Upjohn Company, Kalamazoo, Michigan 49001.
authors.forename: R A
authors.initials: RA
authors.lastname: Conradi
authors.forename: A R
authors.initials: AR
authors.lastname: Hilgers
authors.forename: N F
authors.initials: NF
authors.lastname: Ho
authors.forename: P S
authors.initials: PS
authors.lastname: Burton
mesh_terms: D000595:Amino Acid Sequence; D001692:Biological Transport; D002463:Cell Membrane Permeability; D002478:Cells, Cultured / Q000378:metabolism; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology; D006801:Humans; D006860:Hydrogen Bonding; D008954:Models, Biological; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry / Q000493:pharmacokinetics*; D013329:Structure-Activity Relationship
chemical_list: D009842:Oligopeptides