Purification and characterization of a novel exo-β-1,3-1,6-glucanase from the fruiting body of the edible mushroom Enoki (Flammulina velutipes)

Abstract

To elucidate the role of β-glucanases in the cell-wall degradation involved in morphogenesis, an exo-β-1,3-1,6-glucanase (FvBGL1) was purified from fruiting bodies of the edible mushroom Enoki (Flammulina velutipes), and its enzymatic properties were studied. At least three β-glucanases were detected in the crude extract by zymogram assay when 1% laminarin was used as substrate. The molecular mass of FvBGL1 was estimated by SDS-PAGE to be 80 kDa. The optimum pH and temperature for the action of FvBGL1 were 6.1 and 60°C respectively. FvBGL1 was completely inactivated by 1 mM mercuric ions. FvBGL1 hydrolyzed F. velutipes cell-wall β-glucan as well as β-1,3- and β-1,6-glucans from various sources with glucose as the only reaction product. Transglucosylation was observed when the enzyme acted on laminarinonaose. FvBGL1 can be assumed to degrade F. velutipes cell-wall β-1,3-glucan, but most probably acts more efficiently in concert with other endogenous β-glucan degrading enzymes.