Browsing by Subject "Docking"

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    Inactivation of lipoxygenase and cyclooxygenase by natural betalains and semi-synthetic analogues
    (Elsevier, 2014-01-13) Vidal, Pedro J.; García Carmona, Francisco; Gandía Herrero, Fernando; López Nicolás, José Manuel; Bioquímica y Biología Molecular "A"
    Betalains are natural pigments characteristic of plants of the order Caryophyllales. In this work, the role of betalains in the anti-inflammatory activity described for plant extracts is analysed in terms of the inactivation of the enzymes involved in the biochemical response (lipoxygenase and cyclooxygenase). Pure natural betalains and semi-synthetic analogues are demonstrated to promote a significant reduction of the enzymes activity. Reactions were followed spectrophotometrically and by HPLC-DAD. Phenethylamine-betaxanthin was the most potent in the inactivation of cyclooxygenase, with a reduction of 32% of the control activity at 125 lM, while the natural pigment betanidin and a betalain analogue derived from indoline resulted as the most potent inactivators of lipoxygenase, with IC50 values of 41.4 and 40.1 lM, respectively. Molecular docking studies revealed that betalains interact with the lipoxygenase amino acids involved in substrate binding and with Tyr-385 and Ser-530 close to the yclooxygenase active site, interfering in enzyme catalysis.
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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.