Purification and characterization of a thermostable mycelial lectin from basidiomycete Lentinus squarrosulus

Abstract

Lectins are non-immune carbohydrate-binding proteins or glycoproteins with specific binding sites for certain glycoconjugates. Fungal lectins have been documented for their antitumour, antiproliferative, immunomodulatory, hypotensive and insecticidal effects. In the present study, a mycelial lectin having molecular mass 55 kDa has been purified and characterized from Lentinus squarrosulus. Biological action spectrum of the lectin revealed agglutination of all human blood types (A, B, O, AB), goat, sheep, rabbit and pig erythrocytes. Neuraminidase treatment of blood type O erythrocytes considerably augmented hemagglutination titre. Carbohydrate inhibition studies showed its high affinity to mucin and asialofetuin. Lectin was purified by a combination of ammonium sulphate precipitation, dialysis, ion exchange chromatography and gel filtration chromatography. Optimum pH for lectin activity was observed to be 6.5-8.0 and optimum temperature was 25-30°C. Lectin showed poor pH stability and was stable within pH 7.0-7.5. It was highly thermostable and could withstand temperature upto 70°C. Lectin activity was sensitive to ethylenediaminetetraacetic acid and denaturants. © 2013 Versita Warsaw and Springer-Verlag Wien.