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Spectrophotometric Characterization of the Action of Tyrosinase on p-Coumaric and Caffeic Acids: Characteristics of o-Caffeoquinone

Lookup NU author(s): Dr Jose Munoz Munoz

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Abstract

© 2017 American Chemical Society. New methods are proposed to determine the activity of tyrosinase on caffeic and p-coumaric acids. Because o-quinone from caffeic acid is unstable in its presence, it has been characterized through spectrophotometric measurements of the disappearance of coupled reducing agents, such as nicotinamide adenine dinucleotide reduced form. It has also been characterized by a chronometric method, measuring the time that a known concentration of ascorbic acid takes to be consumed. The activity on p-coumaric acid has been followed by measuring the formation of o-quinone of caffeic acid at the isosbestic point originated between caffeic acid and o-caffeoquinone and measuring the formation of o-quinone at 410 nm, which is stable in the presence of p-coumaric acid (both of them in the presence of catalytic amounts of caffeic acid, maintaining the ratio between p-coumaric acid and caffeic acid constant; R = 0.025). The kcat value of tyrosinase obtained for caffeic acid was higher than that obtained for p-coumaric acid, while the affinity was higher for p-coumaric acid. These values agree with those obtained in docking studies involving these substrates and oxytyrosinase.


Publication metadata

Author(s): Garcia-Jimenez A, Munoz-Munoz JL, Garcia-Molina F, Teruel-Puche JA, Garcia-Canovas F

Publication type: Article

Publication status: Published

Journal: Journal of Agricultural and Food Chemistry

Year: 2017

Volume: 65

Issue: 16

Pages: 3378-3386

Print publication date: 26/04/2017

Online publication date: 07/04/2017

Acceptance date: 07/04/2017

ISSN (print): 0021-8561

ISSN (electronic): 1520-5118

Publisher: American Chemical Society

URL: https://doi.org/10.1021/acs.jafc.7b00446

DOI: 10.1021/acs.jafc.7b00446


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