title: The transport of amino acids, amino acid derivatives and ions across ion-exchange membranes.
abstract: The passage of inorganic salts, glucose, amino acids and peptides across polystyrene-backed double membranes (negative-positive fixed-charge junctions) was studied in a two-compartment cell and compared to a known cellular system, the Ehrlich-Lettre ascites carcinoma. It was concluded that passage proceeds by a 1:1 exchange of diffusing ions in the membrane. The more rapidly transported systems reflected an increased probability of exchange in all cases, as evidenced both by a saturation effect and by the degree to which the space charge was perturbed at the membrane. The amino group (as NH3+) of the amino acid involved in the exchange process was vital for transport. The presence of a second amino group, either ionized or as -NH2, accelerated the exchange. The presence of electron-attracting groups on the side chain or of a methyl group on the alpha carbon also facilitated passage. Cation dependence was seen. Passage was hindered by a second carboxyl group, an alcoholic group, or a lengthened side chain. Use of double membranes permits experimental electrode transport modelling and may facilitate design of a drug delivery system.
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism; D004058:Diffusion; D005947:Glucose / Q000378:metabolism; D007477:Ions / Q000378:metabolism; D008567:Membranes, Artificial; D051379:Mice; D013329:Structure-Activity Relationship
chemical_list: D000596:Amino Acids; D007477:Ions; D008567:Membranes, Artificial; D005947:Glucose