Interpreting Ion Fluxes to Channel Arrays in Monolayers

Abstract

The exponentially decaying permeability model interprets the chronoamperometric currents arising from Tl+ reduction at a Hg electrode covered with a phospholipid monolayer (DOPC) containing gramicidin monomer by combining three processes: (i) the diffusion of an ion to a membrane surface with an array of channels, (ii) the conformational dynamics of the individual channels, and (iii) the passage of the ion through the channels. The introduction of a variable permeability allows us to uncouple the diffusion from the heterogeneous processes, given that the concentration of a species at the active surface can be obtained by semi-integration of the currents. Consideration of a reverse step for the dehydration process at the mouth of the channel allows the analysis of potential steps away from diffusion-limited conditions where a Nernstian-like behavior of the relevant parameter is observed. The model has been successfully applied to data with all trans retinol or benzo-alpha-pyrene as additive to the phospholipid monolayer and to monolayers without any additive at all.

Structural Biology of a Major Signaling Network that Regulates Plant Abiotic Stress: The CBL-CIPK Mediated Pathway

“…Another mechanism for membrane localization involves a single transmembrane helix at the N -terminal of CBL10, to target the sensor to the vacuole [12] and to the plasma membrane [11]. Additionally, SOS3 contains a region rich of lysines that could interact with phospholipids in a process called snorkeling (Figure 7) [53,54]. This polybasic sequence might be important since Ishitani et al .…”

Electrochemistry of mercury supported phospholipid monolayers and bilayers

“…The transport of ions through the gramicidin channel was analysed in very precise detail in later papers where a current versus voltage plot for Tl + through the channel was derived together with the effect of lipid modifiers thereon. The mathematical treatment isolated the channel transport from the diffusion to the channel and the Tl + reduction process [45].…”

Phase phenomena in supported lipid films under varying electric potential

“…2,13,14,34 There exist also plausible theoretical (phenomenological) approaches to the problem. 10,[15][16][17] It remains, however, largely undetermined what type of transition is reflected by each peak in the C(V ) profile, 34 because such phenomenological hypotheses based on indirect observations cannot be easily verified in a supporting experiment that could reveal the resulting molecular (re-)arrangements. A better understanding and theoretical description in such cases requires further research, which can also be based on modelling with the aid of numerical methods.…”

“…Such experiments are based on measuring conductivity, charge capacity and ion-permeability of the adsorbed material. The aim usually is either (i) studying the interfacial reactions and structural transformations in response to varying electric field, 3,[10][11][12][13][14][15][16][17] or (ii) using the electrochemical phenomena in molecular sensing devices, e.g. bio-and taste sensors.…”