Enzymic membrane pumps for specific active transport of small hydrophilic molecules: improvement of the process

The use of a phosphatase and a kinase covalently bound on both parts of a p orous artificial membrane has led us to demonstrate that two opposite react ions occurring at a pore entrance/exit and in unstirred layers can behave a s a specific membrane pump. Such an enzymic pump was found to be able to co ncentrate specifically a given small phosphorylated molecule against its ch emical gradient. The corresponding theoretical analysis of such a phenomeno n predicted that both the kinetics of this transport and the concentration ratio expected in the receiving chamber of a diffusion cell might be improv ed. The comparison of four different membrane structures has led us to corr oborate experimentally the predictions of this new theory. With the most ap propriate membrane used in this study, a concentration ratio of nine times was obtained in 500 min. (C) 1999 Elsevier Science B,V, All rights reserved .