Shunt Concept for Specific Active Transport Using Enzymatic Membranes: Review and Prospects

Artifical enzymatic membranes (AEMs) were conceived with the aim of replicating the active transport found in vivo. The shunt concept has recently emerged from the use of two enzymes catalysing two opposite reactions occurring on both parts of a porous charged membrane (+ or −) and able to specifically add/remove (or the contrary) a charged group (+ or −) on the selected molecule to be transported. Historically, the Phosphatase (P)/Kinase (K) couple (or its inverse), frequently found in nature, was selected for creating these shunts. Modelling of these transports was realized using the Nernst-Planck equation. In parallel, experimental studies were conducted proving that these shunt topologies, involving enzymatic membranes, lead to specific and active solute transports at physiological temperature and pressure. Issuing from this concept, recent technological prospects, such as the specific separation and concentration of (L) substrate from the (D/L) racemic mixture and the selective transport of neutral molecules by electrophoresis, are presented. This review presents the main results obtained using polymeric membranes linked to enzymes with the aim of replicating the active transport found in vivo.