title: L-Dopa synthesis catalyzed by tyrosinase immobilized in poly(ethyleneoxide) conducting polymers.
abstract: 1-3,4-Dihydroxy phenylalanine called as l-Dopa is a precursor of dopamine and an important neural message transmitter and it has been a preferred drug for the treatment of Parkinson's disease. In this study, with regards to the synthesis of L-Dopa two types of biosensors were designed by immobilizing tyrosinase on conducting polymers: thiophene capped poly(ethyleneoxide)/polypyrrole (PEO-co-PPy) and 3-methylthienyl methacrylate-co-p-vinylbenzyloxy poly(ethyleneoxide)/polypyrrole (CP-co-PPy). PEO-co-PPy and CP-co-PPy were synthesized electrochemically and tyrosinase immobilized by entrapment during electropolymerization. L-Tyrosine was used as the substrate for L-Dopa synthesis. The kinetic parameters of the designed biosensors, maximum reaction rate of the enzyme (Vmax) and Michaelis Menten constant (Km) were determined. Vmax were found as 0.007 μmol/(minelectrode) for PEO-co-PPy matrix and 0.012 μmol/(minelectrode) for CP-co-PPy matrix. Km values were determined as 3.4 and 9.2 mM for PEO-co-PPy and CP-co-PPy matrices, respectively. Optimum temperature and pH, operational and shelf life stabilities of immobilized enzyme were also examined.
authors: Department of Chemistry, Karamanoglu Mehmetbey University, 70100 Karaman, Turkey. yildizhb@kmu.edu.tr
authors: Huseyin Bekir
authors: HB
authors: Yildiz
authors: Salim
authors: S
authors: Caliskan
authors: Musa
authors: M
authors: Kamaci
authors: Abdullah
authors: A
authors: Caliskan
authors: Hasim
authors: H
authors: Yilmaz
mesh_terms: D055162:Biocatalysis; D004553:Electric Conductivity; D004566:Electrodes; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007980:Levodopa / Q000138:chemical synthesis* / Q000737:chemistry; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry; D011758:Pyrroles / Q000138:chemical synthesis / Q000737:chemistry; D013696:Temperature
chemical_list: D004800:Enzymes, Immobilized; D011108:Polymers; D011758:Pyrroles; C067635:polypyrrole; D011092:Polyethylene Glycols; D007980:Levodopa; D014442:Monophenol Monooxygenase