Search Results - "VARÓN, RAMÓN"

Hydrogen Peroxide Helps in the Identification of Monophenols as Possible Substrates of Tyrosinase by GARCÍA-MOLINA, Mary of the Sea, MUÑOZ-MUÑOZ, Joseph Luis, BERNA, Joseph, RODRÍGUEZ-LÓPEZ, Joseph Neptune, VARÓN, Ramón, GARCÍA-CÁNOVAS, Francis

“…Tyrosinase exists in three forms in the catalytic cycle depending on the oxidation state of the copper: met- (E m ), oxy-(E ox ), and deoxy-(E d ). When…”
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Kinetic Study of the Oxidation of Quercetin by Mushroom Tyrosinase by Fenoll, Lorena G, García-Ruiz, Pedro A, Varón, Ramón, García-Cánovas, Francisco

“…The kinetic behavior of mushroom tyrosinase in the presence of the flavonol quercetin was studied. This flavonol was oxidized by mushroom tyrosinase and the…”
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Stopped-Flow and Steady-State Study of the Diphenolase Activity of Mushroom Tyrosinase by Rodríguez-López, José Neptuno, Fenoll, Lorena G, García-Ruiz, Pedro Antonio, Varón, Ramón, Tudela, José, Thorneley, Roger N. F, García-Cánovas, Francisco

“…The reaction of mushroom (Agaricus bisporus) tyrosinase with dioxygen in the presence of several o-diphenolic substrates has been studied by steady-state and…”
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Kinetic Analysis of a Model for Double Substrate Cycling: Highly Amplified ADP (and/or ATP) Quantification by Valero, Edelmira, Varón, Ramón, García-Carmona, Francisco

“…A mathematical description has been made of an enzyme amplification mechanism involving the coupling of two substrate cycles. In this amplification system one…”
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Kinetic characterization of the substrate specificity and mechanism of mushroom tyrosinase by Espin, J.C, Varon, R, Fenoll, L.G, Gilabert, M.A, Garcia-Ruiz, P.A, Tudela, J, Garcia-Canovas, F

“…This paper reports a quantitative study of the effect of ring substituents in the 1‐position of the aromatic ring on the rate of monophenol hydroxylation and…”
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Analysis and interpretation of the action mechanism of mushroom tyrosinase on monophenols and diphenols generating highly unstable o-quinones by Fenoll, Lorena G., Rodrı́guez-López, José Neptuno, Garcı́a-Sevilla, Francisco, Garcı́a-Ruiz, Pedro Antonio, Varón, Ramón, Garcı́a-Cánovas, Francisco, Tudela, José

“…Tyrosinase can act on monophenols because of the mixture of met- (E m) and oxy-tyrosinase (E ox) which exists in the native form of the enzyme. The latter form…”
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Reaction mechanism to explain the high kinetic autoactivation of tyrosinase by Peñalver, Maria J., Fenoll, Lorena G., Rodríguez-López, José N., García-Ruiz, Pedro A., García-Molina, Francisco, Varón, Ramón, García-Cánovas, Francisco, Tudela, José

“…The autoactivation of tyrosinase acting on monophenols has been quantitatively characterised by a new kinetic parameter, the rate autoactivation factor (RAF)…”
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Enzymatic Synthesis of 3′-Hydroxyacetaminophen Catalyzed by Tyrosinase by Valero, Edelmira, Lozano, M. Isabel, Varón, Ramón, García-Carmona, Francisco

“…3′‐Hydroxyacetaminophen, a catechol metabolite of N‐acetyl‐p‐aminophenol (acetaminophen) and N‐acetyl‐m‐aminophenol (a structural analogue of acetaminophen and…”
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effect of a natural antioxidant on the stability of heat-treated paprika by Gomez Ladron de Guevara, R, Bernabeu, R, Picazo, M.I, Gonzalez, M, Varon, R

“…Summary The colour loss occurring in a paprika made from the dehydrated fruits of pepper, Capsicum annuum L. var. Ocal (control), was compared with the colour…”
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Action mechanism of tyrosinase on meta- and para-hydroxylated monophenols by Fenoll, L G, Rodríguez-López, J N, Varón, R, García-Ruiz, P A, García-Cánovas, F, Tudela, J

“…The relationship between the structure and activity of meta- and para-hydroxylated monophenols was studied during their tyrosinase-catalysed hydroxylation and…”
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Kinetics of a self-amplifying substrate cycle: ADP–ATP cycling assay by VALERO, Edelmira, VARÓN, Ramón, GARCÍA-CARMONA, Francisco

“…A kinetic study of an ATP–ADP amplification cyclic system involving the enzymes adenylate kinase, pyruvate kinase and l-lactate dehydrogenase has been made…”
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Continuous Spectrophotometric Method for Determining Monophenolase and Diphenolase Activities of Pear Polyphenoloxidase by ESPÍN, JUAN CARLOS, MORALES, MERCEDES, VARÓN, RAMÓN, TUDELA, JOSÉ, GARCÍA-CÁNOVAS, FRANCISCO

“…ABSTRACT A continuous spectrophotometric method was based on the coupling reaction between 3‐methyl‐2‐benzothiazolinone hydrazone (MBTH) and the quinone…”
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Tyrosinase action on monophenols: evidence for direct enzymatic release of o-diphenol by Rodrı́guez-López, José Neptuno, Fenoll, Lorena G., Peñalver, Marı́a J., Garcı́a-Ruiz, Pedro Antonio, Varón, Ramón, Martı́nez-Ortı́z, Francisco, Garcı́a-Cánovas, Francisco, Tudela, José

“…Using gas chromatography–mass spectrometry, the direct enzymatic release of o-diphenol (4- tert-butylcatechol) during the action of tyrosinase on a monophenol…”
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Indirect inactivation of tyrosinase in its action on 4-tert-butylphenol by Muñoz-Muñoz, Jose Luis, García-Molina, María del Mar, García-Molina, Francisco, Varon, Ramón, García-Ruiz, Pedro Antonio, Rodríguez-López, Jose Neptuno, García-Cánovas, Francisco

“…Under anaerobic conditions, the o-diphenol 4-tert-butylcatechol (TBC) irreversibly inactivates met and deoxytyrosinase enzymatic forms of tyrosinase. However,…”
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Time-dependent inhibition of grape polyphenol oxidase by tropolone by Valero, Edelmira, Garcia-Moreno, Manuela, Varon, Ramon, Garcia-Carmona, Francisco

“…A kinetic study of inhibition of the catecholase activity of grape polyphenol oxidase by tropolone has been made. The results obtained showed that tropolone…”
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Calibration of a Clark-Type oxygen electrode by tyrosinase-catalyzed oxidation of 4-tert-butylcatechol by Rodriguez-López, J N, Ros-Martínez, J R, Varón, R, García-Cánovas, F

“…A procedure for calibrating a Clark-type oxygen electrode is described. This method is based on the oxidation of 4-tert-butylcatechol (TBC) by O2 catalyzed by…”
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Oxidation by mushroom tyrosinase of monophenols generating slightly unstable o‐quinones by Fenoll, Lorena G., Rodríguez‐López, José N., García‐Sevilla, Francisco, Tudela, José, García‐Ruiz, Pedro Antonio, Varón, Ramón, García‐Cánovas, Francisco

“…Tyrosinase can act on monophenols because of the mixture of mettyrosinase (Em) and oxytyrosinase (Eox) that exists in the native form of the enzyme. The latter…”
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Kinetic study of the effect of metabisulfite on polyphenol oxidase by Valero, Edelmira, Varon, Ramon, Garcia-Carmona, Francisco

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A kinetic study of the generation and decomposition of some phenothiazine free radicals formed during enzymatic oxidation of phenothiazines by peroxidase-hydrogen peroxide by Vázquez, A, Tudela, J, Varón, R, García-Cánovas, F

“…A kinetic study of the oxidation of four different phenothiazines (Pts) by peroxidase-hydrogen peroxide was carried out. The free radical formed during the…”
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Action of ellagic acid on the melanin biosynthesis pathway by Ortiz-Ruiz, Carmen Vanessa, Berna, Jose, Tudela, Jose, Varon, Ramon, Garcia-Canovas, Francisco

“…Highlights • Ellagic acid is not an inhibitor but an alternative substrate of tyrosinase. • The Michaelis and catalytic constants of ellagic acid are 138 μM…”
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