Dehydrogenase-Modified Electrodes Functioning as Biocatalyst Electrodes

负载固定化酶的修饰电极可以通过固定化酶的辅基与电极表面之间的电子交换来电催化氧化或还原酶的底物。这种类型的电极，生物催化剂电极，可以用于生物传感器，生物反应器和生物燃料电池等新的应用。采用不可逆吸附法将荧光假单胞菌的D-葡萄糖酸脱氢酶（GADH）固定在泛醌混合碳糊电极表面。1.1.99.3 GADH修饰电极可以电催化氧化D-葡萄糖酸，泛醌作为碳糊电极和固定化酶之间的电子传递介质。考察了各种因素对电极对D-葡萄糖酸盐的电流响应的影响，并用作者提出的包埋型介体生物催化电极理论对实验结果进行了解释。考察了脱氢酶修饰物作为电流型传感器的实际应用。对苯醌（BQ）可代替泛醌作为介体，在电极表面用半透膜包裹酶层是有效的。结果表明，BQ掺杂的GADH碳糊电极可用作D-葡萄糖酸传感器。提出了一种高灵敏度测量基底的新方法，该方法在测试溶液中等待一段给定的时间后使用线性扫描伏安法。其他酶如寡糖脱氢酶和甘油脱氢酶也被固定在碳糊电极表面。脱氢酶修饰电极对底物有电流响应，可作为底物的传感器。

Modified electrodes carrying immobilized dehydrogenases could oxidize or reduce the substrate of the enzymes electrocatealytically by exchanging electrons between the prosthetic group of the immobilized enzyme and the electrode surface. This ytpe of electrodes, biocatalyst electrodes, could be used in such novel applications as biosensors, bioreactors, and biofuel cells. We immobilized D-gluconate dehydrogenase, GADH,(EC 1.1.99.3) form Pseudomanas fluorescens on the surface of a ubiquinone-mixed carbon paste electrode by irreversible adsorption. The GADH modified electrodes could oxidize-D-gluconate electrocatalytically, with ubiquinone serving as an electron transfer mediator between the carbon paste electrode and the immobilized enzyme. The effect of various factors on the current response of the electrode to D-gluconate was investigated, and the results were explained by the theory of biocatalyst electrode with an entrapped mediator which an entrapped mediator which was derived by the author. The practical use of the dehydrogenase modifeid as an amperometric sensor was examined. p-Benzoquinone, BQ, could be used as a mediator in place of ubiquinone and the presence of a semipermeable membrance coating the enzyme layer on the electrode surface was effective. It has been shown that the film-coated GADH carbon paste electrode with mixed-in BQ can be used as a D-gluconate sensor. A novel method measuring the substrate at high sensitivity was proposed, which uses a linear sweep voltammetry after a given period of waiting time in a test solution. Other dehydrogenases such as oligosaccharide dehydrogenase and glycerol dehydrogenase were also immobilized on the surface of carbon paste electrode with mixed-in BQ. The dehydrogenase modified electrodes showed currnet response to their substrates, and could be used as the sonsors for the substrates.