Purification and Characterization of a Novel Exo-β-1,3-1,6-glucanase from the Fruiting Body of the Edible Mushroom Enoki (Flammulina velutipes)

To elucidate the role of beta-glucanases in the cell-wall degradation involved in morphogenesis, an exo-beta-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 beta-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 degrees C respectively. FvBGL1 was completely inactivated by 1 mM mercuric ions. FvBGL1 hydrolyzed F. velutipes cell-wall beta-glucan as well as beta-1,3- and beta-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 beta-1,3-glucan, but most probably acts more efficiently in concert with other endogenous beta-glucan degrading enzymes.