Dimethoxyphenol oxidase activity of different microbial blue multicopper proteins

2,6-Dimethoxyphenol is a versatile substrate for Pyricularia oryzae laccase , PpoA from Marinomonas mediterranea, phenoxazinone synthase from Streptomy ces antibioticus and mammalian ceruloplasmin. In addition, in cellular extr acts of microorganisms expressing other blue multicopper proteins with no e nzymatic activity previously described, such as Escherichia coli (copper re sistance CueO), Pseudomonas syringae and Xanthomonas campestris (copper res istance CopA), Bacillus subtilis (sporulation protein CotA) and Saccharomyc es cerevisiae (iron transporter Fet3p), laccase activity is detected under appropriate conditions. This oxidase activity can be spectrophotometrically followed by the oxidation of 2,6-dimethoxyphenol. Specific staining after SDS-PAGE is also possible for some of these proteins. This detection assay can facilitate the study of the multiple functions that such proteins seem to carry out in a variety of microorganisms. (C) 2001 Federation of Europea n Microbiological Societies. Published by Elsevier Science BN. All rights r eserved.