title: Formation of stable vesicles from N- or 3-alkylindoles: possible evidence for tryptophan as a membrane anchor in proteins.
abstract: Twelve indole derivatives have been prepared and studied. Five were 1-substituted: 1, methyl; 2, n-hexyl; 3, n-octyl; 4, n-octadecyl; and 5, cholestanyloxycarbonylmethyl. Four were 3-substituted: 6, methyl; 7, n-hexyl; 8, n-octyl; and 9, n-octadecyl. Three were disubstituted as follows: 10, 1-n-decyl-3- n-decyl; 11, 1-methyl-3-n-decyl; and 12, 1,3-bis(n-octadecyl)indole. Sonication of aqueous suspensions afforded stable aggregates from 3-5 and 8-12. Laser light scattering, dye entrapment, and electron microscopy were used to characterize the aggregates. Aggregates formed from N-substituted indoles proved to be more robust than those formed from 3-alkylindoles. A stable monolayer formed from 3-n-octadecylindole but not from N- or 1,3-disubstituted analogues by using a Langmuir-Blodgett trough. The formation of aggregates was explained in terms of stacking by the relatively polar indole headgroup. In the monolayer experiment, this force was apparently overwhelmed by H-bonding interactions with the aqueous phase.
authors.affiliation: Bioorganic Chemistry Program, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8103, St. Louis, Missouri 63110, USA.
authors.forename: E
authors.initials: E
authors.lastname: Abel
authors.forename: S L
authors.initials: SL
authors.lastname: De Wall
authors.forename: W B
authors.initials: WB
authors.lastname: Edwards
authors.forename: S
authors.initials: S
authors.lastname: Lalitha
authors.forename: D F
authors.initials: DF
authors.lastname: Covey
authors.forename: G W
authors.initials: GW
authors.lastname: Gokel
mesh_terms: D002850:Chromatography, Gel; D020285:Cryoelectron Microscopy; D005456:Fluorescent Dyes / Q000737:chemistry; D007211:Indoles / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008567:Membranes, Artificial; D008854:Microscopy, Electron; D008956:Models, Chemical; D008958:Models, Molecular; D011506:Proteins / Q000737:chemistry*; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D005456:Fluorescent Dyes; D007211:Indoles; D008567:Membranes, Artificial; D011506:Proteins; D014364:Tryptophan