Structural highlights
Publication Abstract from PubMedCatechol oxidases (EC 1.10.3.1) catalyse the oxidation of o-diphenols to their corresponding o-quinones. These oxidases contain two copper ions (CuA and CuB) within the so-called coupled type 3 copper site as found in tyrosinases (EC 1.14.18.1) and haemocyanins. The crystal structures of a limited number of bacterial and fungal tyrosinases and plant catechol oxidases have been solved. In this study, we present the first crystal structure of a fungal catechol oxidase from Aspergillus oryzae (AoCO4) at 2.5-A resolution. AoCO4 belongs to the newly discovered family of short-tyrosinases, which are distinct from other tyrosinases and catechol oxidases because of their lack of the conserved C-terminal domain and differences in the histidine pattern for CuA. The sequence identity of AoCO4 with other structurally known enzymes is low (less than 30 %), and the crystal structure of AoCO4 diverges from that of enzymes belonging to the conventional tyrosinase family in several ways, particularly around the central alpha-helical core region. A diatomic oxygen moiety was identified as a bridging molecule between the two copper ions CuA and CuB separated by a distance of 4.2-4.3 A. The UV/vis absorption spectrum of AoCO4 exhibits a distinct maximum of absorbance at 350 nm, which has been reported to be typical of the oxy form of type 3 copper enzymes. The crystal structure of an extracellular catechol oxidase from the ascomycete fungus Aspergillus oryzae.,Hakulinen N, Gasparetti C, Kaljunen H, Kruus K, Rouvinen J J Biol Inorg Chem. 2013 Sep 17. PMID:24043469[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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