title: Tyrosinase: polybrene noncovalent complexes in water-ethanol mixtures.
abstract: Formation of noncovalent complexes between tyrosinase from mushrooms and a cationic polyelectrolyte, polybrene (PB, poly (1,5-dimethyl-1,5-diazaundecamethyelene) bromide), was shown to activate and stabilize tyrosinase in water-ethanol mixtures. In the reaction of catechol oxidation in aqueous solutions, catalytic activity (k(cat)) of tyrosinase-PB complex ([PB]/[tyrosinase] molar ratio 100:1, per mole of polymer) in a wide range of pH was higher than that of free tyrosinase. In aqueous solutions and in water-ethanol mixtures at moderate concentrations of ethanol (10-40% v/v), the value of k(cat) of tyrosinase-PB complex exceeded the activity of free enzyme, from 1.2-2-fold, accompanied by the essential (up to 10-fold) increase in the value of the specificity constant (k(cat)/K(m)). The results are of practical importance for the construction of biocatalysts working successfully in polar organic media.
authors.affiliation: Department of Chemical Enzymology, Chemical Faculty, Moscow State University, 199899 Moscow, Russia.
authors.forename: Stepan
authors.initials: S
authors.lastname: Shipovskov
authors.forename: Andrey
authors.initials: A
authors.lastname: Levashov
mesh_terms: D000363:Agaricales / Q000201:enzymology; D002384:Catalysis; D002396:Catechols / Q000378:metabolism; D004800:Enzymes, Immobilized / Q000378:metabolism*; D000431:Ethanol / Q000737:chemistry; D006583:Hexadimethrine Bromide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D014442:Monophenol Monooxygenase / Q000737:chemistry / Q000378:metabolism*; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D002396:Catechols; D004800:Enzymes, Immobilized; D012997:Solvents; D014867:Water; D000431:Ethanol; D006583:Hexadimethrine Bromide; D010088:Oxidoreductases; D014442:Monophenol Monooxygenase; C034221:catechol