Comparative Study of the Hemagglutinating Activity of Lectins Isolated from Different Developmental Stages of Culinary-Medicinal Oyster Mushroom, Pleurotus ostreatus (Jacq.: Fr.) Kumm. (Agaricomycetideae)

Abstract

During the cultivation of Pleurotus ostreatus on wheat straw and distillery effluent containing substrate, the primordia exhibited very low hemagglutinating activity. However, the hemagglutinating activity of the matured fruiting bodies and vegetative mycelium at harvesting time reached extremely high values, 32,051,282 and 69,930,069 U/mg, respectively. Four fractions of proteins (3.5−105 kDa) from the matured fruiting bodies and five fractions of proteins (125, 110, 69, 8, and 1.5−2 kDa) from the vegetative mycelium extract with lectin activity were obtained after gel chromatography through the column Toyopearl HW-55F. N-acetyl-D-glucosamine and N-acetyl-D-galactosamine were the most potent inhibitors of hemagglutinating activity of fraction I (0.19 mM) from the fruiting body extract. Galactose exerted the highest inhibitory effect toward lectins in other fractions at concentrations of 1.56−3.125 mM. Unlike the fruiting body lectins, the mycelial lectins displayed a predominant specificity toward mannose. CuCl2 and MgCl2 dose-dependently inhibited the lectin activity of mycelial fraction V. On the contrary, the hemagglutinating activity of this fraction was doubled in the presence of 5 and 10 mM MnCl2. The lectin activity of fractions II and V was halved in the presence of 5 mM EDTA, whereas 10 mM β-mercaptoethanol sharply decreased the hemagglutinating activity of fractions II-IV and completely inhibited the activity of fraction V, indicating the presence of Ca and cystine, respectively, in carbohydrate-binding centers of lectins.