A composite enzymatic membrane (CEM), made up of two enzymatic membranes carrying two enzymes catalyzing two opposite reactions on either side of a permeable negatively charged membrane was used in this study. The phosphatase/kinase enzyme couple was chosen to make CEM permitting the active and selective transport of small-phosphorylated molecules. Here, we show that a CEM involving the alkaline phosphatase/glycerokinase enzyme couple permits, in a compartmentalized system, not only the separation of the D and L forms of a racemic mixture Of (D/L) glycerophosphate, but also the simultaneous concentration of the L form alone. (C) 2006 Elsevier Inc. All rights reserved.