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Abstract

Transport phenomena occurring in biological membrane systems are not only correlated with differences of the chemical and/or electrochemical potentials of the solutes and solvent across the membranes but rather with chemical reactions taking place at the membrane surfaces or within the membranes. The chemical reactions governing or affecting transport across biological membranes are essentially catalyzed by enzymes attached to the membrane matrices. For that reason, biological membranes contain immobilized enzymes and/or complete enzyme systems (organelles). The transport phenomena controlled by enzyme reactions are sometimes termed “active transport”. In this connection, it should be noted that by far not all transport phenomena coupled with chemical reactions deserve the term “active transport” [1]. Most of those transport phenomena correlated with a chemical reaction rather ought to be named “facilitated or coupled transport” [2,3,4,5]. Nevertheless, it is appropriate to use synthetic membranes, containing immobilized enzymes, in order to model transport phenomena occuring in biological systems coupled with enzyme reactions. Several authors have previously reported on such systems [6,7,8,9].