Transmembrane pores formed by synthetic p-octiphenyl beta-barrels with internal carboxylate clusters: regulation of ion transport by pH and Mg(2+)- complexed 8-aminonaphthalene-1,3,6-trisulfonate.
Design, synthesis, and study of a synthetic barrel-stave supramolecule with p-octiphenyl "staves," beta-sheet "hoops," and hydrophobic exterior as well as internal carboxylate clusters are reported. Ion transport experiments indicate the formation of transmembrane pores at 5 < pH < 7 with nanomolar activity. Blockage of dye efflux from spherical bilayers by external Mg(OAc)(2) and internal 8-aminonaphthalene-1,3,6-trisulfonate is suggestive for weakly cooperative (n = 1.16) formation of aspartate-Mg(2+)-8-aminonaphthalene-1,3,6-trisulfonate complexes within the barrel-stave supramolecule (K(D) = 2.9 mM). Corroborative evidence from structural studies by circular dichroism spectroscopy is provided and discussed with emphasis of the importance of internal charge repulsion for pore formation and future applications toward binding and catalysis within supramolecular synthetic pores.
Das
Gopal
G
Department of Organic Chemistry, University of Geneva, CH-1211 Geneva, Switzerland.
Matile
Stefan
S
D001692:Biological Transport; D002264:Carboxylic Acids / Q000737:chemistry*; D002462:Cell Membrane / Q000737:chemistry; D002942:Circular Dichroism; D003902:Detergents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004530:Egg Yolk / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry* / Q000378:metabolism; D008956:Models, Chemical; D008958:Models, Molecular; D009281:Naphthalenes / Q000737:chemistry*; D017830:Octoxynol / Q000494:pharmacology; D010713:Phosphatidylcholines / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D013053:Spectrophotometry; D013997:Time Factors; D014466:Ultraviolet Rays
D002264:Carboxylic Acids; D003902:Detergents; D005456:Fluorescent Dyes; D007477:Ions; D009281:Naphthalenes; D010713:Phosphatidylcholines; D017830:Octoxynol; C046465:8-amino-1,3,6-naphthalenetrisulfonic acid; D008274:Magnesium