2026-09-21T12:28:57Zhttps://riubu.ubu.es/oai/request

oai:riubu.ubu.es:10259/47662024-07-24T11:21:21Zcom_10259_9476com_10259.4_106com_10259_2604col_10259_9477

00925njm 22002777a 4500 dc Ferraroni, Marta . author Westphal, Adrie H. . author Borsari, Marco . author Tamayo Ramos, Juan Antonio author Briganti, Fabrizio . author Graaff, Leo H. de . author Berkel, Willem J. H. van . author 2017-01 The ascomycete Aspergillus niger produces several multicopper oxidases, but their biocatalytic properties remain largely unknown. Elucidation of the crystal structure of A. niger laccase McoG at 1.7 Å resolution revealed that the C-terminal tail of this glycoprotein blocks the T3 solvent channel and that a peroxide ion bridges the two T3 copper atoms. Remarkably, McoG contains a histidine (His253) instead of the common aspartate or glutamate expected to be involved in catalytic proton transfer with phenolic compounds. The crystal structure of H253D at 1.5 Å resolution resembles the wild type structure. McoG and the H253D, H253A and H253N variants have similar activities with 2,2’-azino-bis(3- ethylbenzothiazoline-6-sulphonic acid or N,N-dimethyl-p-phenylenediamine sulphate. However, the activities of H253A and H253N with 2-amino-4-methylphenol and 2-amino-4-methoxyphenol are strongly reduced compared to that of wild type. The redox potentials and electron transfer rates (ks) of wild type and variants were determined (McoG wt E°’ is +453 mV), and especially the reduced ks values of H253A and H253N show strong correlation with their low activity on phenolic compounds. In summary, our results suggest that the His253 adaptation of McoG can be beneficial for the conversion of phenolic compounds. 2353-1746 http://hdl.handle.net/10259/4766 10.1515/boca-2017-0001 Aspergillus niger crystal structure laccase redox potential metalloprotein multicopper oxidase Structure and function of Aspergillus niger laccase McoG