p-Hydroxyphenylacetate-3-hydroxylase. A two-protein component enzyme

Arunachalam, Usha and Massey, Vincent and Vaidyanathan, CS (1992) p-Hydroxyphenylacetate-3-hydroxylase. A two-protein component enzyme. In: Journal of Biological Chemistry, 267 (36). pp. 25848-25855.

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Abstract

p-Hydroxyphenylacetate-3-hydroxylase, an inducible enzyme isolated from the soil bacterium Pseudomonas putida, catalyzes the conversion of p-hydroxyphenylacetate to 3,4-dihydroxyphenylacetate. The enzyme requires two protein components: a flavoprotein and a colorless protein referred to as the coupling protein. The flavoprotein alone in the presence of p-hydroxyphenylacetate and substrate analogs catalyzes the wasteful oxidation of NADH with the stoichiometric generation of H2O2. A 1:1 complex of the flavoprotein and coupling protein is required for stoichiometric product formation. Such complex formation also eliminates the nonproductive NADH oxidase activity of the flavoprotein. A new assay measuring the product formation activity of the enzyme was developed using homoprotocatechuate-2,3-dioxygenase, as monitoring the oxidation of NADH was not sufficient to demonstrate enzyme activity. The coupling protein does not seem to have any redox center in it. Thus, this 2-component flavin hydroxylase resembles the other aromatic hydroxylases in that the only redox chromophore present is FAD.

Item Type:	Journal Article
Publication:	Journal of Biological Chemistry
Publisher:	The American Society for Biochemistry and Molecular Biology
Additional Information:	Copyright of this article belongs to The American Society for Biochemistry and Molecular Biology.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	02 May 2011 05:19
Last Modified:	02 May 2011 05:19
URI:	http://eprints.iisc.ac.in/id/eprint/37316

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