title: Stereospecificity of mushroom tyrosinase immobilized on a chiral and a nonchiral support.
abstract: Mushroom tyrosinase was immobilized from an extract onto glass beads covered with the cross-linked totally cinnamoylated derivates of d-sorbitol (sorbitol cinnamate) and glycerine (glycerine cinnamate). The enzyme was immobilized onto the support by direct adsorption, and the quantity of immobilized tyrosinase was higher for sorbitol cinnamate, the support with the higher number of esterified hydroxyls per unit of monosacharide, than for glycerine cinnamate. The results obtained from the stereospecificity study of the monophenolase and diphenolase activity of immobilized mushroom tyrosinase are reported. The enantiomers L-tyrosine, DL-tyrosine, D-tyrosine, L-dopa, DL-dopa, D-dopa, L-alpha-methyldopa, DL-alpha-methyldopa, L-isoprenaline, DL-isoprenaline, L-adrenaline, DL-adrenaline, L-noradrenaline, and D-noradrenaline were assayed with tyrosinase immobilized on a chiral support (sorbitol cinnamate), whereas L-tyrosine, DL-tyrosine, D-tyrosine, L-dopa, DL-dopa, D-dopa, L-alpha-methyldopa, and DL-alpha-methyldopa were assayed with tyrosinase immobilized on a nonchiral support (glycerine cinnamate). The same Vmax(app) values for each series of enantiomers were obtained. However, the Km(app) values were different, the l isomers showing lower values than the dl isomers, whereas the highest Km(app) value was obtained with d isomers. No difference was observed in the stereospecificity of tyrosinase immobilized on a chiral (sorbitol cinnamate) or nonchiral (glycerine cinnamate) support.
authors.affiliation: Grupo de Química de Carbohidratos y Biotecnología de Alimentos (QCBA), Departamento de Química OrgAnica, Facultad de Química, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain.
authors.forename: María Elisa
authors.initials: ME
authors.lastname: Marín-Zamora
authors.forename: Francisco
authors.initials: F
authors.lastname: Rojas-Melgarejo
authors.forename: Francisco
authors.initials: F
authors.lastname: García-Canovas
authors.forename: Pedro Antonio
authors.initials: PA
authors.lastname: García-Ruiz
mesh_terms: D004800:Enzymes, Immobilized / Q000737:chemistry*; D007700:Kinetics; D014442:Monophenol Monooxygenase / Q000737:chemistry*; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D004800:Enzymes, Immobilized; D014442:Monophenol Monooxygenase