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Structural and functional characterization of ochratoxinase, a novel mycotoxin-degrading enzyme
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry. (Dobritzsch)
2014 (English)In: Biochemical Journal, ISSN 0264-6021, E-ISSN 1470-8728, Vol. 462, no 3, 441-452 p.Article in journal (Refereed) Published
Abstract [en]

Ochratoxin, with ochratoxin A as the dominant form, is one of the five major mycotoxins most harmful to humans and animals. It is produced by Aspergillus and Penicillium species and occurs in a wide range of agricultural products. Detoxification of contaminated food is a challenging health issue. In the present paper we report the identification, characterization and crystal structure (at 2.2 angstrom) of a novel microbial ochratoxinase from Aspergillus niger. A putative amidase gene encoding a 480 amino acid polypeptide was cloned and homologously expressed in A. niger. The recombinant protein is N-terminally truncated, thermostable, has optimal activity at pH similar to 6 and 66 degrees C, and is more efficient in ochratoxin A hydrolysis than carboxypeptidase A and Y, the two previously known enzymes capable of degrading this mycotoxin. The subunit of the homo-octameric enzyme folds into a two-domain structure characteristic of a metal dependent amidohydrolase, with a twisted TIM (triosephosphateisomerase)-barrel and a smaller beta-sandwich domain. The active site contains an aspartate residue for acid base catalysis, and a carboxylated lysine and four histidine residues for binding of a binuclear metal centre.

Place, publisher, year, edition, pages
2014. Vol. 462, no 3, 441-452 p.
Keyword [en]
metal-dependent amidohydrolase, mycotoxin, ochratoxin degradation, protein crystal structure
National Category
Chemical Sciences
URN: urn:nbn:se:uu:diva-235169DOI: 10.1042/BJ20140382ISI: 000341802100006PubMedID: 24947135OAI: oai:DiVA.org:uu-235169DiVA: diva2:761253
Available from: 2014-11-06 Created: 2014-10-29 Last updated: 2015-01-13Bibliographically approved

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