Supramolecular ion channels from a transmembrane bischolic acid derivative showing two discrete conductances

Abstract

Bischolic acid derivative 1 linked by m-xylylene dicarbamate at the 3,3'-position was synthesized and the single ion channel properties were examined. Compound 1 showed two clearly distinct conductances, 9.5 (type A) and 25.3 pS (type B), under 500 mM KCl symmetric salt conditions, whereas various conductances, ranging from 5-20 pS, were observed in the tetramethylether analogue reported previously. Results indicate that the replacement of four methylether groups with hydroxyls at the 7, 7', 12, and 12' positions in the bischolic acid framework influences the stability of aggregated (supramolecular) ion channel structures. Ion permeability ratios (potassium/chloride and potassium/sodium) for each type of channel were also determined.

A Standard Structure for Bile Acids and Derivatives

“…The subject has been reviewed recently [18]. On the other hand, the head-tail structure of BS allows the synthesis of head-to-head [19], head-to-tail [20], and tail-to-tail [21] dimers. The ratio of number of steroid groups to number of charged groups (equal to 1 in natural BS) can be easily modified for monomers, dimers, and oligomers.…”

Biomaterials made of bile acids

“…When the arms are modified with photosensitive groups, the molecules are sensitive to both solvents and UV light [96] . Similar molecules were made as artificial ion channels that can transport K + across the phospholipid bilayers (Figure 18) [97,98] . Oligomers derived from bile acids can also act as gelators.…”

Bile salts and derivatives: Rigid unconventional amphiphiles as dispersants, carriers and superstructure building blocks

“…These sites define the head and the tail of the compound, respectively [93], and, consequently, head-to-tail [94], head-to-head [95] and tail-to-tail [96] preparing BSDs (see above), this bond was the most explored one by our research groups for the synthesis of BS dimers. For getting the amide formation at C3, the -hydroxyl group has to be substituted by an amino one [99], while the carboxylic group at C24 may be used as such or transformed into an amino one [100].…”