title: Tannic acid interferes with the commonly used laccase-detection assay based on ABTS as the substrate.
abstract: Laccase enzymatic activity in biological samples is usually detected spectrophotometrically through its capacity to oxidize several specific aromatic compounds. One of the most commonly used substrates is the compound 2-2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), which becomes green-blue coloured when it is oxidized by laccase. In this work we study the interference of tannic acid with the spectrophotometric assay to detect laccase by using ABTS as the substrate. Our data show that under the normal reaction conditions of this assay, but in the absence of any catalyst, tannic acid is able to carry out the chemical reduction of the oxidized specie of ABTS, thus decreasing the overall detectable laccase-activity values observed when this enzyme is present in the reaction mixture. Therefore, our results represent an important warning concerning a commonly used method for measuring, detecting or screening laccases in biological samples that may content tannic acid or structural-related molecules.
authors.affiliation: Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, E-28040, Madrid, Spain.
authors.forename: M C
authors.initials: MC
authors.lastname: Terrón
authors.forename: M
authors.initials: M
authors.lastname: López-Fernández
authors.forename: J M
authors.initials: JM
authors.lastname: Carbajo
authors.forename: H
authors.initials: H
authors.lastname: Junca
authors.forename: A
authors.initials: A
authors.lastname: Téllez
authors.forename: S
authors.initials: S
authors.lastname: Yagüe
authors.forename: A
authors.initials: A
authors.lastname: Arana-Cuenca
authors.forename: T
authors.initials: T
authors.lastname: González
authors.forename: A E
authors.initials: AE
authors.lastname: González
mesh_terms: D052160:Benzothiazoles; D005658:Fungi / Q000201:enzymology; D047348:Hydrolyzable Tannins / Q000737:chemistry* / Q000494:pharmacology; D007202:Indicators and Reagents; D042845:Laccase / Q000032:analysis* / Q000378:metabolism; D010084:Oxidation-Reduction; D013451:Sulfonic Acids / Q000737:chemistry*
chemical_list: D052160:Benzothiazoles; D047348:Hydrolyzable Tannins; D007202:Indicators and Reagents; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D042845:Laccase