title: An amperometric inhibitor biosensor for the determination of reduced glutathione (GSH) without any derivatization in some plants.
abstract: In this study, an amperometric biosensor based on cucumber tissue homogenate was developed for the determination of glutathione. Cucumber (Cucumis sativus L.) tissue homogenate was used as the biological material. The cucumber tissue homogenate was cross-linked with gelatine using glutaraldehyde and fixed on a pretreated teflon membrane. The principle of the measurements was based on the determination of the decrease in the differentiation of oxygen level which had been caused by the inhibition of ascorbate oxidase in the biological material by glutathione. Determinations were carried out by standard curves which were obtained by the measurement of the decrease in the consumed oxygen level related to glutathione concentration. Optimization and characterization studies of the biosensor were carried out and a linearity in the gamma-L-glutamyl-L-cysteinyl-glycine (GSH) concentration range 0.1-2 microM was obtained when 600 microM ascorbic acid was used as a substrate. The repeatability experiments (n = 7) revealed that for 1.5 microM GSH, the average value (x), standard deviation (S.D.) and variation coefficient (C.V.) were 1.517 microM, 4.72 x 10(-5) 3.11%, respectively. The biosensor useful lifetime was at least 2 months. The results of some plant samples analyzed with the presented biosensor agreed well with the spectrophotometric method (Ellman's reagent) used as a reference.
authors.affiliation: Biochemistry Department, Faculty of Science, Ege University, Bornova, Izmir 35100, Turkey. mkemals@sci.ege.edu.tr
authors.forename: Mustafa Kemal
authors.initials: MK
authors.lastname: Sezgintürk
authors.forename: Erhan
authors.initials: E
authors.lastname: Dinçkaya
mesh_terms: D001204:Ascorbate Oxidase / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D002384:Catalysis; D018553:Cucumis sativus / Q000378:metabolism*; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005978:Glutathione / Q000032:analysis* / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D010936:Plant Extracts / Q000737:chemistry*; D010940:Plant Proteins / Q000032:analysis / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013696:Temperature
chemical_list: D010936:Plant Extracts; D010940:Plant Proteins; D001204:Ascorbate Oxidase; D005978:Glutathione