The effect of structure of the enzyme-fixed polymers on the reactivity of enzyme

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Immobilized enzymes are considered to be a kind of modified enzymes and used in the fields of bioreactors and sensors. The reactivity of enzymes which is not in the form of their homogeneous solutions was observed by Nelson and Griffins. There have been lots of papers concerning modified enzymes, especially sensors. The objective of this study is to clarify the effect of polymers which have copper in membranes on the reactivity of immobilized ascorbic acid oxidlse (ASOD), because ASOD is a special enzyme containing copper and the relationships between the function and the membrane potential. The sensor which has ASOD in the membrane are now used in order to know the concentration of ascorbic acid in raw fishes or Vitamin C.At first, poly (vinyl chloride) having N-methyl-N-carboxymethyl dithiocarbamate which is able to form a chelate complex, was prepared and used as a polymer for combining ASOD. A thin membrane was casted from the solution to which ASOD was added. Then copper was impre … More gnated into the membrane. Oxygen electrode system was combined with membranes prepared. A current reduction was measured by oxygen electrode. The relationships between the concentration of L-ascorbic acid and the decrease of the electric current, were obtained. However, the current reduction of the copper-containing chelate polymer, was not so high as that of non-chelate polymer. It is considered that crosslinking in the membrane caused the decrease of the swelling and reduced oxygen diffusivity. In stead, using salt-forming polymers such as copoly (methyl methacrylate-acrilic acid) gave the higher decrease of the electric current. This phenomena suggest that both hydration of the membrane and the presence of copper enhanced the response of the sensor.Thin membranes of Chloromethylated polymay-gamma-methyl-L-glutamate were prepared on the surface of a porous polypropyrene sheet by the spin-caseted method and quariernized with trimthylamine. ASOD was fixed by the identical way. This type of the sensor was found to be excellent in both sensitivity and durability.Also, the relationships between response of the enzyme-fixed composite membranes and their change of the membrane potential was obtained and analyzed with our new membrane potential theory. Less