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Purification and Properties of l-4-Hydroxymandelate Oxidase from Pseudomonas convexa

Bhat, Santhoor G and Vaidyanathan, S Chelakara (1976) Purification and Properties of l-4-Hydroxymandelate Oxidase from Pseudomonas convexa. In: European Journal of Biochemistry, 68 (2). pp. 323-331.

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An inducible membrane-bound l-4-hydroxymandelate oxidase (decarboxylating) from Pseudomonas convexa has been solubilized and partially purified. It catalyzes the conversion of l-4-hydroxymandelic acid to 4-hydroxybenzaldehyde in a single step with the stoichiometric consumption of O2 and liberation of CO2. The enzyme is optimally active at pH 6.6 and at 55 oC. It requires FAD and Mn2+ for its activity. The membrane-bound enzyme is more stable than the solubilized and purified enzyme. After solubilization it gradually loses its activity when kept at 5 oC which can be fully reactivated by freezing and thawing. The Km values for DL-4-hydroxymandelate and FAD are 0.44 mM and 0.038 mM respectively. The enzyme is highly specific for DL-4-hydroxymandelic acid. DL-3,4-Dihydroxymandelic acid competitively inhibited the enzyme reaction. From the Dixon plot the Ki for DL-3,4-dihydroxymandelic acid was calculated to be 1.8 × 10−4 M. The enzyme is completely inactivated by thiol compounds and not affected by thiol inhibitors. The enzyme is also inhibited by denaturing agents, heavy metal ions and by chelating agents.

Item Type: Journal Article
Publication: European Journal of Biochemistry
Publisher: John Wiley and Sons, Inc.
Additional Information: Copyright of this article belongs to John Wiley & Sons, Inc. 1999-2009.
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 10 Dec 2009 12:40
Last Modified: 19 Sep 2010 05:48
URI: http://eprints.iisc.ac.in/id/eprint/24073

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