A lectin was isolated from fruiting bodies of the mushroom Gymnopilus spectabilis (GSL) by ionic exchange chromatography. The lectin agglutinates mouse red cells exhibiting broad specificity towards several monosaccharides including the N-acetylneuraminic acid. Agglutination was also inhibited by the glycoproteins: fetuin, lactoferrin, and recombinant erythropoietin. GSL is a glycoprotein possessing 16 % of carbohydrates; the SDS-PAGE showed two bands with molecular mass of 52.1 and 64.4 kDa. Isoelectric focusing displayed microheterogeneity, with two bands at pIs 5.1 and 5.3. The lectin was stable between pH 2 and pH 8 while at pH 10, the agglutination decayed to 50 % of initial activity. Incubation at 40 and 80 °C led to 50 and 100 % loss in activity of the lectin, respectively. Synthesized GSL-Sepharose interacts with serum pregnant mare gonadotropin, and at least two subpopulations of this glycoprotein were separated. There was no interaction between transferrin and soluble GSL while a partial recognition was achieved with GSL-Sepharose. The terminal sialic acid seems to play an active role in modifying the interaction with GSL, depending if the lectin is in a soluble or immobilized form. The purified lectin inhibited in vitro the growth of Staphylococcus aureus and Aspergillus niger.

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Basidiomycetes are able to biodegrade waste and xenobiotic molecules through the production of extracellular enzymes. For example, white-rot fungi produce lignin-degrading enzymes which are capable of efficiently decolorizing dye solutions. Many mushrooms also produce lectins, a group of proteins which bind specifically to the carbohydrates in glycoconjugates. Several fungal lectins target their specificities towards oligosaccharides present in mammalian glycoproteins, thus constituting excellent ligands for the preparation of affinity adsorbents useful in isolation and characterization of these glycoproteins. In this study we isolated and characterized two different proteins, a lectin and a laccase, present in extracts from Punctularia atropurpurascens. The lectin isolated from the mycelium extract, was immobilized on activated-Sepharose and used to evaluate the interaction with three glycoproteins. The adsorbent was able to efficiently adsorb and elute bovine lactoferrin, constituting a promising tool for the purification of this glycoprotein. In vitro experiments revealed that the lectin also exhibited antimicrobial activity against Aspergillus niger. Laccase activity was detected in the extracellular extract from P. atropurpurascens. This enzyme, in both soluble and immobilized forms, was able to degrade Remazol Brilliant Blue R and Acid Blue 25 dyes. The biological activities found in this fungus demonstrate its potential for various biotechnological applications.