Fungal tyrosinases: new prospects in molecular characteristics, bioengineering and biotechnological applications

Abstract

Tyrosinases are type‐3 copper proteins involved in the initial step of melanin synthesis. These enzymes catalyse 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. In fungi, tyrosinases are generally associated with the formation and stability of spores, in defence and virulence mechanisms, and in browning and pigmentation. First characterized from the edible mushroom Agaricus bisporus because of undesirable enzymatic browning problems during postharvest storage, tyrosinases were found, more recently, in several other fungi with relevant insights into molecular and genetic characteristics and into reaction mechanisms, highlighting their very promising properties for biotechnological applications. The limit of these applications remains in the fact that native fungal tyrosinases are generally intracellular and produced in low quantity. This review compiles the recent data on biochemical and molecular properties of fungal tyrosinases, underlining their importance in the biotechnological use of these enzymes. Next, their most promising applications in food, pharmaceutical and environmental fields are presented and the bioengineering approaches used for the development of tyrosinase‐overproducing fungal strains are discussed.

Some kinetic properties of polyphenol oxidase obtained from dill (Anethum graveolens)

“…This enzyme catalyzes two distinct reactions involving molecular oxygen [4,5]: (i) the o-hydroxylation of monophenol (monopheolase activity) and (ii) the oxidation of o-diphenol to o-quinones (diphenolase activity). The kinetic reaction mechanism of polyphenol oxidase has been elucidated [6,7,8].…”

Transcriptional Regulation and Responses in Filamentous Fungi Exposed to Lignocellulose

“…Fungi with high expression or activity of tyrosinases, the enzymes that de-toxify phenolic compounds [169], could detoxify the mixed culture efficiently thus preventing inhibition of the other fungus. Thus, de-toxifying mechanisms originating from one fungus could have beneficial effects on growth of both fungi, and thus on saccharification in mixed cultures.…”

Screening, Localization and Activity of Mushroom Tyrosinase from Various Developmental Growth Phases of Pleurotus florida

“…The limit of these applications remains in the fact that native fungal tyrosinase are generally intracellular and produced in low quantity (Halaouli et al, 2006). The exploitation of tyrosinase from various parts of mushroom is considered, for Pleurotus florida.…”