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Kinetic characterization of the oxidation of catecolamines and related compounds by laccase.

Abstract：

: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.

journal_name

Int J Biol Macromol

journal_title

International journal of biological macromolecules

authors

Manzano-Nicolas J,Taboada-Rodriguez A,Teruel-Puche JA,Marin-Iniesta F,Garcia-Molina F,Garcia-Canovas F,Tudela-Serrano J,Muñoz-Muñoz JL

doi

10.1016/j.ijbiomac.2020.07.112

subject

Has Abstract

pub_date

2020-12-01 00:00:00

pages

1256-1266

eissn

0141-8130

issn

1879-0003

pii

S0141-8130(20)33860-5

journal_volume

164

pub_type

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Kinetic characterization of the oxidation of catecolamines and related compounds by laccase.