Browsing by Subject "Kinetic"

Now showing 1 - 3 of 3
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    Cinética de hidroxilación y oxidación de compuestos fenólicos por Polifenol Oxidasa de uva Monastrell (Vitis Vinifera)
    (Murcia: Universidad de Murcia, Servicio de Publicaciones, 1987) Sánchez Ferrer, Álvaro; Cabanes Cos, Juana; Bru Martínez, Roque; Facultad de Biología
    La enzima polifenol oxidasa ha sido purificada a partir de uva Monastrell mostrando actividad tanto en la oxidación de monofenoles (cresolasa) como en la de o-difenoles (catecolasa). Los parámetros cinéticos, Km y temperatura óptima, han sido evaluados en ambas actividades. La actividad cresolasa presenta un período de retardo característico, que puede ser modificado por la temperatura, la concentración de enzima, la presencia de o-difenoles y la concentración de sustrato.
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    Feasibility of adsorption kinetic models to study carrier-mediated transport of heavy metal ions in emulsion liquid membranes
    (2022-01-03) León, G.; Gómez, E.; Miguel, B.; Hidalgo, A.M.; Gómez, M.; Murcia, M.D.; Guzmán, M.A.; Ingeniería Química
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    Kinetic characterization of the oxidation of catecolamines and related compounds by laccase
    (Elsevier, 2020-07-25) Taboada Rodriguez, Amaury; Manzano Nicolás, Jesús; Teruel Puche, José Antonio; Marín Iniesta, Fulgencio; García Cánovas, Francisco; García Molina, Francisco; Tudela Serrano, José; Muñoz Muñoz, José Luis; Bioquímica y Biología Molecular A
    The pathways of melanization and sclerotization of the cuticle in insects are carried out by the action of laccases on dopamine and related compounds. In this work, the laccase action of Trametes versicolor (TvL) on catecholamines and related compounds has been kinetically characterized. Among them, dopamine, l-dopa, l-epinephrine, l-norepinephrine, dl-isoprenaline, l-isoprenaline, dl-α-methyldopa, l-α-methyldopa and l-dopa methylester. A chronometric method has been used, which is based on measuring the lag period necessary to consume a small amount of ascorbic acid, added to the reaction medium. The use of TvL has allowed docking studies of these molecules to be carried out at the active site of this enzyme. The hydrogen bridge interaction between the hydroxyl oxygen at C-4 with His-458, and with the acid group of Asp-206, would make it possible to transfer the electron to the T1 Cu-(II) copper centre of the enzyme. Furthermore, Phe-265 would facilitate the adaptation of the substrate to the enzyme through Π-Π interactions. To kinetically characterize these compounds, we need to take into consideration that, excluding l-dopa, l-α-methyldopa and dl-α-methyldopa, all compounds are in hydrochloride form. Because of this, first we need to kinetically characterize the inhibition by chloride and, after that, calculate the kinetic parameters KM and VmaxS. From the kinetic data obtained, it appears that the best substrate is dopamine. The presence of an isopropyl group bound to nitrogen (isoprenaline) makes it especially difficult to catalyse. The formation of the ester (l-dopa methyl ester) practically does not affect catalysis. The addition of a methyl group (α-methyl dopa) increases the rate but decreases the affinity for catalysis. l-Epinephrine and l-norepinephrine have an affinity similar to isoprenaline, but faster catalysis, probably due to the greater nucleophilic power of their phenolic hydroxyl.