Active transport of glycerol-3-phosphate with artificial enzyme membranes: A new kinetic model for active transport processes

Abstract

An approach to the mechanism which may govern translocation and active transport system is presented. Two artificial enzyme membranes with immobilized kinase and immobilized phosphatase, respectively, were used close together to separate two unequal compartments of a specially designed diffusion cell in order to mimic solute active transport. Experiments were conducted and both translocation and active transport of glycerol-3-phosphate were obtained. The theoretical analysis of this active transport-like phenomenon, which underlines the key role played by the charge distribution on the membrane and the diffusion layers existing close to the membrane-bound enzymes is presented and is in good agreement with the experimental data. Our results mainly demonstrate that under specific conditions, the association of kinase and phosphatase activities on both parts of a porous membrane functions as an enzymic pump which performs active transport. Such results may be of general significance and lead us to suggest that a carrier could be substituted by two catalytic activities bound on both parts of a structure of channel type and catalysing two opposite reactions in diffusion layers.