Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6488038 | Enzyme and Microbial Technology | 2018 | 34 Pages |
Abstract
A putative laccase-like gene, GPPO, encoding a protein of 17.2â¯kDa and belonging to the multicopper oxidase family, was cloned and overexpressed in Escherichia coli cells. The purified recombinant protein GPPO is homodecameric protein with a molecular weight of 171.6â¯kDa. GPPO was not detected the ultraviolet-visible spectroscopy (UV/Vis) spectrum of typical laccases. Co2+ or Cu2+ was essential for substrate oxidation of GPPO, and the enzyme contained 1â¯mol of Co or Cu per mole of protein. The optimum pH required for the oxidation of 2,2â²-azino-bis(3-ethylbenzothazoline-6-sulfonate) (ABTS) and 2,6-dimethoxyphenol (DMP) was 4.5 and 5.5, respectively, and the optimum temperature was 75â¯Â°C. The half-life of heat inactivation was about 8â¯min at 80â¯Â°C and 90â¯min at 90â¯Â°C, in the presence of Cu2+ and Co2+, respectively. The catalytic efficiency (kcat/Km) of GPPO containing Co2+ was 68 times higher than that of GPPO containing Cu2+. The enzyme reaction was inhibited by conventional inhibitors of laccase like metal chelators and thiol compounds. GPPO incubated with Cu2+ or Co2+ for 48â¯h decolorizes 45% or 47% of Nile blue, respectively. This is the first report of a novel thermostable polyphenol oxidase that shows the cobalt-dependent laccase activity and dye decolorization ability.
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Authors
Soo-Jung Moon, Han-Woo Kim, Sung-Jong Jeon,