Nucleoside oxidase‐modified carbon paste electrode containing quinone: Cathodic current response to nucleosides

Abstract

The cathodic current for the reduction of benzoquinone at a glassy carbon electrode was increased in the presence of nucleoside oxidase and inosine. This was attributed to the regeneration of benzoquinone from hydroquinone by the laccaselike reaction of the enzyme, the rate of which depended on the concentration of inosine in the solution. Accordingly, an enzyme electrode for nucleosides was constructed by immobilizing nucleoside oxidase behind a dialysis membrane on a carbon paste electrode containing p-benzoquinone or hydroquinone. The current response of the electrode to nucleosides was studied, and the results were discussed on the basis of the laccaselike activity of the enzyme. The nucleoside oxidase-modified electrode was tested as an amperometric enzyme electrode for nucleosides and could be used at least for three weeks.k7W WORDS: Biosensors, nucleosides, nucleoside oxidase. A"TR0DUCTIONConsiderable attention has been given to the coupling of electrode reaction with an enzymatic reaction, in which the substrate of the enzyme can be oxidized or reduced electroenzymatically, i.e., by bioelectrocatalysis [ 1-31. Molecules serving as redox mediators are usually used to achieve the electron transfer coupling, and enzyme electrodes relying on this principle of current response, mediated amperometric enzyme electrodes, have been constructed (4, 51. A variety of redox molecules including redox polymers have been studied for the mediated electron transfer coupling based on glucose oxidase and other oxidoreductases [ 1-31. Similar coupling without mediators has also been reported between ordinary electrodes (such as carbon and metal surfaces), and several kinds of oxidoreductases [ 6-91.This article describes a new type of electroenzymatic coupling different from the above two coupling schemes, which rely on the unique properties of the enzyme used: nucleoside oxidase [NOD] from Pseudomom maltophiria LB-86 (10-131. NOD has a molecular weight of 'To whom correspondence should be addressed. 8 1992 VCH Publishers, Inc. 1040-0397/92/$3.50 + .25 891 892 Ikeda et al.

Reduction of Different Nitro-Compounds on Electroenzymatic System: Cytochrome c Reductase-NAD(P)H Modified Carbon Paste Electrode

“…The enzyme was puri®ed as described in the literature [16]. Electrophoresis of the enzyme after puri®cation was homogeneous and showed one band corresponding to 78 000 according to the literature.…”

“…However, the principal interest of the present study is focused to plasma and urine samples. In this scope, potential interferents in the range from 0 to À0.7 V (versus AgaAgCl) should be consider metabolites like ethanol, glucose-6-phosphate, glycerol and L-lactate at À0.15 V, pH 8.5 [15]; inosine, thymidine, cytidine, adenosine, uridine, deoxycytosine and deoxyadenosine at À0.1 V [16]; phenol, catechol, 4-cresol, hydroquinone, pyrogallol, L-tyrosine, tyramine, 3,4-dihydroxyphenylalanine, chlorogenic acid at À0.1 V [17]; hydrogen peroxide, methanol, 1-propanol, 2-propanol, 1-butanol at À0.05 V [18±22]; bilirubin at À0.2 V [23]; dopamine, epinephrine at À0.2 V [24]; D-alanine, D-valine, D-leucine, D-isoleucine, D-serine, D-aspartic acid, D-glutamic acid, D-lysine, D-histidine, Darginine, D-phenylalanine, D-tryptophen, D-methionine, D-proline at À0.05 V [25,26]; and all 20 common L-amino acids at À0.05 V [18,20,26].…”

Carbon paste electrodes modified with enzymes, tissues, and cells

“…In the presence of molecular oxygen and a nucleoside, hydroquinone is oxidized to BQ, which in turn can be electrochemically rereduced back to form hydroquinone. By adsorbing nucleoside oxidase onto hydroquinone modified carbon paste electrodes all nucleosides could be monitored [64]. By adding 5'-nucleotidase to the contacting solution, nucleotides could be monitored as well [79].…”

Significance of Uricase in Oxidase-Induced Oxidative Coloring Reaction ofp-Phenylenediamine

“…The expression of such alternative function of the enzyme−substrate complex is not unique for UOD. For example, nucleoside oxidase from Pseudomonas maltophilia LB-86 is reported to show laccase-like activity only in the presence of the substrate (nucleoside) together with the inherent nucleoside oxidase activity. ,

6 Panel A: Effect of the UOD concentration on the H 2 O 2 concentration-dependent oxidative polymerization rate of PPD (ν) in the presence of 1.0 mM uric acid at pH 7.0 and at 30 °C under deaerated conditions. The UOD concentration/U mL -1 : (○) 0, (·) 23.3, (▴) 45.8, (◆) 88.7.

…”

“…For example, nucleoside oxidase from Pseudomonas maltophilia LB-86 is reported to show laccase-like activity only in the presence of the substrate (nucleoside) together with the inherent nucleoside oxidase activity. 34,35 Figure 5. Effect of PPD (30.8 mM) on the time-dependent dioxygen concentration change caused by 0.3 U mL -1 of UOD in the presence of 0.1 mM uric acid at pH 7.0 and 30 °C in a space-free and air-tight electrochemical cell.…”