Electrochemical studies of lipophilic ion transport through BLM. The influence of sterols on its transport
✍ Scribed by Lin Ding; Erkang Wang
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 568 KB
- Volume
- 8
- Category
- Article
- ISSN
- 1040-0397
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✦ Synopsis
Cyclic voltammetry was employed to study the influence of stcrols on the lipophilic ion transport through the BLM. The mole fraction of (he sterols (cholesterol, oxidized cholesterol), as referred to total lipid, was varied in a range of 0-0.8. Data demonstrate that a thin-layer model is suitable to this BLM system, By this model, the number ofcharges transported per lipophilicion, the concentration of the ion in the membrane hulk phase and the aqueous/membrane phase partition coefficient could be calculated. These parameters proved that sterols had an obvious influence on the lipophilic ion transport. Cholesterol had a stronger influence on the ion transport than oxidized cholesterol. Its incorporation into egg lecithin membranes increased the partition coefficient of the ion up to more than 3-fold. Yet, oxidized cholesterol incorporated into egg lecithin membranes only increased the up to less than 2-fold, and the /3 had no great variation at different oxidized cholesterol mole fractions. The higher obtained was partly due to the trace amount of solvent existing in the core of the lipid bilayers. At the different sterol mole fractions, combining the change of 0 with the changc of peak current, we also concluded that sterols had somewhat inhibiting effect on the ion transport at the higher sterols mole fraction (> 0.4). These results are explained in terms of the possible change of dipole potential of the membrane produccd by sterols and the decrease of the membrane fluidity caused by thecondensation effect ofsterols and the thinning effect caused by sterols. The substituting group (in the oxidized cholesterol) had some inhibiting effects on the ion transport at higher mole fractions (oxidized cholesterol mole fraction > 0.4).