title: Magnetic enzyme membranes as active elements of electrochemical sensors. Lactose, saccharose, maltose bienzyme electrodes.
abstract: The direct monitoring of sugars such as lactose, maltose, saccharose is not only useful at the applied point of view but also at the fundamental point of view for studying enzymology, especially in microbiology and fermentation. Benzyme systems were extensively used in solution for analytical applications in industry and medicine. The progress in the field of immobilization of bienzyme systems [1-3], especially within membranes [4-5], makes possible the production of new analytical devices. From the studies dealing with concentration profiles in artificial enzyme membranes [14], evidence was obtained for a well defined relationship between the local concentration of a metabolite and concentration of the first substrate in the bulk solution. In the described systems a substrate is transformed into glucose within a membrane, the glucose is then transformed in gluconic acid with a local oxygen consumption. The local pO2 level is linked to the glucose oxidase velocity, which is only linked to the glucose production, that is to say to the concentration of the first substrate. The enzyme electrode is based on the transformation of kinetic phenomena (reaction rates) into absolute values (local concentrations) through the diffusion-reaction coupling process. The manufacture of magnetic enzyme electrodes [6] allows convenient use of the active sensors. The pO2 electrode has some adventages, namely the specificity based on the selectivity of the gas permeable membrane and the linear relationship between the oxygen and the output of the electrode. pCO2, pH, ion electrodes give a logarithmic response as a function of the concentration. The grafting of a multienzyme system on a sensor allows a study of sequential systems in a defined context with a measurement of the local concentration of the metabolites. The tool is useful for both kinetics [4] and regulation studies [5].
mesh_terms: D004187:Disaccharides / Q000032:analysis*; D004563:Electrochemistry; D004566:Electrodes; D004798:Enzymes; D005696:Galactosidases; D005949:Glucose Oxidase; D005959:Glucosidases; D007785:Lactose / Q000032:analysis; D008280:Magnetics; D008320:Maltose / Q000032:analysis; D008567:Membranes, Artificial; D008956:Models, Chemical; D010100:Oxygen; D013393:Sucrase; D013395:Sucrose / Q000032:analysis
chemical_list: D004187:Disaccharides; D004798:Enzymes; D008567:Membranes, Artificial; D013395:Sucrose; D008320:Maltose; D005949:Glucose Oxidase; D005696:Galactosidases; D005959:Glucosidases; D013393:Sucrase; D007785:Lactose; D010100:Oxygen