title: Development of a new catalase activity assay for biological samples using optical CUPRAC sensor.
abstract: A novel catalase activity assay was developed for biological samples (liver and kidney tissue homogenates) using a rapid and low-cost optical sensor-based 'cupric reducing antioxidant capacity' (CUPRAC) method. The reagent, copper(II)-neocuproine (Cu(II)-Nc) complex, was immobilized onto a cation-exchanger film of Nafion, and the absorbance changes associated with the formation of the highly-colored Cu(I)-Nc chelate as a result of reaction with hydrogen peroxide (H2O2) was measured at 450 nm. When catalase was absent, H2O2 produced the CUPRAC chromophore, whereas catalase, being an effective H2O2 scavenger, completely annihilated the CUPRAC signal due to H2O2. Thus, the CUPRAC absorbance due to H2O2 oxidation concomitant with Cu(I)-Nc formation decreased proportionally with catalase. The developed sensor gave a linear response over a wide concentration range of H2O2 (0.68-78.6 μM). This optical sensor-based method applicable to tissue homogenates proved to be efficient for low hydrogen peroxide concentrations (physiological and nontoxic levels) to which the widely used UV method is not accurately responsive. Thus, conventional problems of the UV method arising from relatively low sensitivity and selectivity, and absorbance disturbance due to gaseous oxygen evolution were overcome. The catalase findings of the proposed method for tissue homogenates were statistically alike with those of HPLC.
authors.affiliation: Department of Chemistry, Faculty of Engineering, Istanbul University, Avcilar 34320, Istanbul, Turkey.
authors.forename: Burcu
authors.initials: B
authors.lastname: Bekdeşer
authors.affiliation: Department of Chemistry, Faculty of Engineering, Istanbul University, Avcilar 34320, Istanbul, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Özyürek
authors.affiliation: Department of Chemistry, Faculty of Engineering, Istanbul University, Avcilar 34320, Istanbul, Turkey. Electronic address: gkubilay@istanbul.edu.tr.
authors.forename: Kubilay
authors.initials: K
authors.lastname: Güçlü
authors.affiliation: Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Istanbul University, Avcılar 34320, Istanbul, Turkey.
authors.forename: Fulya Üstün
authors.initials: FÜ
authors.lastname: Alkan
authors.affiliation: Department of Chemistry, Faculty of Engineering, Istanbul University, Avcilar 34320, Istanbul, Turkey.
authors.forename: Reşat
authors.initials: R
authors.lastname: Apak
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D015374:Biosensing Techniques; D002138:Calibration; D002374:Catalase / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003300:Copper / Q000378:metabolism*; D057075:Enzyme Assays / Q000379:methods*; D006861:Hydrogen Peroxide / Q000633:toxicity; D008566:Membranes / Q000187:drug effects; D051379:Mice; D055620:Optical Phenomena; D010084:Oxidation-Reduction; D013057:Spectrum Analysis; D014020:Tissue Extracts / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D014020:Tissue Extracts; D003300:Copper; D006861:Hydrogen Peroxide; D002374:Catalase
keywords: Catalase activity; Cupric reducing antioxidant capacity (CUPRAC) assay; Nafion membrane film; Optical sensor