Purification, properties and induction of a specific benzoate-4-hydroxylase from Aspergillus niger (UBC 814)

Reddy, C Chenna and Vaidyanathan, CS (1975) Purification, properties and induction of a specific benzoate-4-hydroxylase from Aspergillus niger (UBC 814). In: Biochimica et Biophysica Acta, 384 (1). 46 -57.

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Abstract

An inducible benzoate-4-hydroxylase has been partially purified from crude extracts of the mycelial felts of Aspergillus niger. This enzyme catalyzes the transformation of benzoate to p-hydroxybenzoate with equimolar consumption of NADPH and O2. It requires tetrahydropteridine as a prosthetic group. The optimum activity was found at pH 6.2 with a Km value at 30°C of 1.6 · 10−4 M for NADPH and 1.3 · 10−4 M for benzoate. Fe2+ (iron) is required for the enzyme activity. The enzyme is stabilized by the inclusion of benzoate, EDTA and glutathione in the extracting buffer. The enzyme is specific for benzoate as substrate. Sulfhydryl group(s) are essential for enzyme activity as indicated by p-chloromercuri-benzoate and N-ethylmaleimide inactivation. Benzoate-4-hydroxylase activity is decreased in the mycelial felts of Aspergillus niger grown in the presence of higher concentrations of benzoate. Maximum activity of the enzyme was observed at 36 h after inoculation.

Item Type:	Journal Article
Publication:	Biochimica et Biophysica Acta
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	22 Jan 2010 05:09
Last Modified:	19 Sep 2010 05:49
URI:	http://eprints.iisc.ac.in/id/eprint/24252

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