4c5y

Publication Abstract from PubMed

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. Here we report the identification, characterization and crystal structure (at 2.2 A) 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~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 homooctameric enzyme folds into a two-domain structure characteristic for a metal dependent amidohydrolase, with a twisted TIM-barrel and a smaller b-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 center.

Structural and functional characterization of ochratoxinase, a novel mycotoxin degrading enzyme.,Dobritzsch D, Wang H, Schneider G, Yu S Biochem J. 2014 Jun 20. PMID:24947135^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.