title: Novel laccase redox mediators: spectral, electrochemical, and kinetic properties.
abstract: The screening of potential redox mediators for laccase was performed using homogeneous enzyme preparations from Coriolus hirsutus and Coriolus zonatus. It was discovered that derivatives of 1-phenyl-3-methyl-pyrazolones were efficient substrates for the laccases. The characterization of two representatives of the 1-phenyl-pyrazolone class, sodium 1-phenyl-3-methyl-4- methylamino-pyrazolone-5-N(4)-methanesulfonate and 1-(3'-sulfophenyl)-3- methylpyrazolone-5, in the reaction catalyzed by laccase was carried out using spectral, electrochemical, and enzyme kinetics methods. The kinetic parameters for the oxidation of the newly discovered substrates were comparable with those for 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) oxidation by laccase. Electrochemical experiments demonstrated that oxidation of these compounds yielded two high-potential intermediates capable of oxidizing veratryl alcohol, which was used as a lignin model substrate, to the corresponding aldehyde and acid. 1-(3'-Sulfophenyl)-3- methylpyrazolone-5 was about 30-40% as effective in degrading veratryl alcohol compared to ABTS as judged from high-performance liquid chromatography kinetic studies. 1-Phenyl-3-methyl-pyrazolones may be of commercial interest for oxidoreductase-catalyzed biodegradation of organic compounds.
authors.affiliation: A.N. Bach Institute of Biochemistry, Russian Academy of Sciences, Leninsky Pr. 33, 119071 Moscow, Russia.
authors.forename: S V
authors.initials: SV
authors.lastname: Shleev
authors.forename: I Gvon
authors.initials: IG
authors.lastname: Khan
authors.forename: I G
authors.initials: IG
authors.lastname: Gazaryan
authors.forename: O V
authors.initials: OV
authors.lastname: Morozova
authors.forename: A I
authors.initials: AI
authors.lastname: Yaropolov
mesh_terms: D001487:Basidiomycota / Q000201:enzymology; D052160:Benzothiazoles; D001592:Benzyl Alcohols / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004563:Electrochemistry; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D042845:Laccase / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D010084:Oxidation-Reduction; D011720:Pyrazoles / Q000737:chemistry / Q000378:metabolism; D013053:Spectrophotometry; D013379:Substrate Specificity; D013451:Sulfonic Acids / Q000737:chemistry / Q000378:metabolism
chemical_list: D052160:Benzothiazoles; D001592:Benzyl Alcohols; D011720:Pyrazoles; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D042845:Laccase; C042197:veratryl alcohol