Mediator-assisted laccase-catalyzed oxidation of 4-hydroxybiphenyl.
The kinetics of oxidation of 4-hydroxybiphenyl (4-HBP) catalyzed by laccase from Polyporus pinsitus was studied in the presence of methyl syringate (MS), which acts as an electron-transfer mediator. Measurements were performed in 0.05 M acetate buffer, pH 5.5, in the presence of 4-HBP, MS, and laccase. It is shown that the oxidation rate of the lowly reactive substrate 4-HBP significantly increases during synergistic action of the highly reactive substrate MS. Bimolecular kinetic constants of interaction between the oxidized form of laccase and MS, the former and 4-HBP, and the oxidized form of MS and 4-HBP were calculated. A kinetic scheme of the synergistic substrate action is suggested; based on this scheme, the dependence of the initial rate on reagent concentration is derived. Analyzing experimental data, we obtained kinetic constants close to those obtained by modeling the processes.
Bratkovskaya
I
I
Institute of Biochemistry, Vilnius, LT-08662, Lithuania. bratkovskaja@bchi.lt
Ivanec
R
R
Kulys
J
J
D001713:Biphenyl Compounds / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D007700:Kinetics; D042845:Laccase / Q000737:chemistry / Q000378:metabolism*; D008956:Models, Chemical; D010084:Oxidation-Reduction / Q000187:drug effects; D011124:Polyporaceae / Q000201:enzymology
D001713:Biphenyl Compounds; C506133:methyl syringate; D005707:Gallic Acid; C019046:4-phenylphenol; D042845:Laccase