Effects of Carbohydrates on the Ion Conductance of the Hemocyanin Channel

Hemocyanin Channel, Planar Lipid Bilayer, Carbohydrates, D ivalent Cations, Protein Conformations The effects o f glucose and sucrose on the ionic conductance properties o f the channel formed by Megathura crenulata hemocyanin in planar lipid bilayers have been studied using membranes of different compositions. It was found that glucose at high concentrations strongly affects the time constants o f the current relaxations observed in membranes containing many channels after a step in the voltage clamp from ground to a positive value. At much lower concentrations both sucrose and glucose strengthened the binding o f Ba2+ to the protein, what in turn has the effect to shift the conductance voltage curve o f the pore towards negative potentials. The possible mechanism underlying these effects and the analogies with other studies on the interaction of sugars and alcohols with proteins have been discussed.