title: Laccase chloride inhibition reduction by an anthraquinonic substrate.
abstract: Due to their low substrate specificity, fungal laccases have a great potential in industrial applications, including the bioremediation of colored wastewaters from textile industry. However, the presence of halides in these effluents (up to 1M NaCl) which inhibit laccases is a drawback for bioremediation processes. In order to develop an efficient enzymatic remediation process for textile dye effluent, the possibility to reduce this halide inhibition is conditioned by a better understanding of the phenomenon. The present study gives a detailed account of the kinetics of chloride inhibition of both ABTS (a model substrate) and ABu62 (an anthraquinonic acid dye) oxidations catalyzed by Trametes versicolor laccase (LacIIIb). Chloride inhibition can be described by a mixed model for ABTS and a non-competitive model for ABu62 and both inhibitions are linear suggesting a single inhibitory site for chloride. Experiments were also conducted in presence of both substrates. An apparent activation of laccase was observed in the presence of ABu62 leading to an enhancement of the oxidation rate of ABTS. The extent of activation increased in the presence of chloride anions. Finally, for the first time to our knowledge, we evidenced that inhibition of ABTS oxidation by chloride can be reduced in the presence of ABu62.
authors.affiliation: Earth and Life Institute, Applied Microbiology, Mycology Unit, Place Croix du Sud 3/6, 1348 Louvain-la-Neuve, Belgium. estelle.enaud@uclouvain.be
authors.forename: Estelle
authors.initials: E
authors.lastname: Enaud
authors.forename: Marie
authors.initials: M
authors.lastname: Trovaslet
authors.forename: Françoise
authors.initials: F
authors.lastname: Naveau
authors.forename: Anne
authors.initials: A
authors.lastname: Decristoforo
authors.forename: Séverine
authors.initials: S
authors.lastname: Bizet
authors.forename: Sophie
authors.initials: S
authors.lastname: Vanhulle
authors.forename: Claude
authors.initials: C
authors.lastname: Jolivalt
mesh_terms: D000880:Anthraquinones / Q000378:metabolism*; D052160:Benzothiazoles / Q000378:metabolism; D001673:Biodegradation, Environmental / Q000187:drug effects; D002712:Chlorides / Q000494:pharmacology*; D004396:Coloring Agents / Q000378:metabolism; D005656:Fungal Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D007700:Kinetics; D042845:Laccase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010084:Oxidation-Reduction; D013379:Substrate Specificity; D013451:Sulfonic Acids / Q000378:metabolism; D013783:Textile Industry; D055454:Trametes / Q000201:enzymology
chemical_list: D000880:Anthraquinones; D052160:Benzothiazoles; D002712:Chlorides; D004396:Coloring Agents; D005656:Fungal Proteins; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D042845:Laccase