5m6b: Difference between revisions
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== Function == | == Function == | ||
[[http://www.uniprot.org/uniprot/PPO4_AGABI PPO4_AGABI]] Copper-containing oxidase that catalyzes both the o-hydroxylation of monophenols and the subsequent oxidation of the resulting o-diphenols into reactive o-quinones, which evolve spontaneously to produce intermediates, which associate in dark brown pigments. Involved in the initial step of melanin synthesis. Melanins constitute a mechanism of defense and resistance to stress such as UV radiations, free radicals, gamma rays, dehydratation and extreme temperatures, and contribute to the fungal cell-wall resistance against hydrolytic enzymes in avoiding cellular lysis. Fungal pigments are also involved in the formation and stability of spores (By similarity). | [[http://www.uniprot.org/uniprot/PPO4_AGABI PPO4_AGABI]] Copper-containing oxidase that catalyzes both the o-hydroxylation of monophenols and the subsequent oxidation of the resulting o-diphenols into reactive o-quinones, which evolve spontaneously to produce intermediates, which associate in dark brown pigments. Involved in the initial step of melanin synthesis. Melanins constitute a mechanism of defense and resistance to stress such as UV radiations, free radicals, gamma rays, dehydratation and extreme temperatures, and contribute to the fungal cell-wall resistance against hydrolytic enzymes in avoiding cellular lysis. Fungal pigments are also involved in the formation and stability of spores (By similarity). | ||
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== Publication Abstract from PubMed == | |||
Tyrosinases are an ubiquitous group of copper containing metalloenzymes that hydroxylate and oxidize phenolic molecules. In an application context the term 'tyrosinase' usually refers to 'mushroom tyrosinase' consisting of a mixture of isoenzymes and containing a number of enzymatic side-activities. We describe a protocol for the efficient heterologous production of tyrosinase 4 from Agaricus bisporus in Escherichia coli. Applying this procedure a pure preparation of a single isoform of latent tyrosinase can be achieved at a yield of 140 mg per liter of autoinducing culture medium. This recombinant protein possesses the same fold as the enzyme purified from the natural source as evidenced by single crystal X-ray diffraction. The latent enzyme can be activated by limited proteolysis with proteinase K which cleaves the polypeptide chain after K382, only one The latent enzyme can amino acid before the main in-vivo activation site. Latent tyrosinase can be used as obtained and enzymatic activity may be induced in the reaction mixture by the addition of an ionic detergent (e.g. 2 mM SDS). The proteolytically activated mushroom tyrosinase shows >50% of its maximal activity in the range of pH 5 to 10 and accepts a wide range of substrates including mono- and diphenols, flavonols and chalcones. | |||
Heterologous expression and characterization of functional mushroom tyrosinase (AbPPO4).,Pretzler M, Bijelic A, Rompel A Sci Rep. 2017 May 12;7(1):1810. doi: 10.1038/s41598-017-01813-1. PMID:28500345<ref>PMID:28500345</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
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== References == | |||
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