PURIFICATION, MOLECULAR AND BIOCHEMICAL CHARACTERIZATION AND BIOLOGICAL APPLICATIONS OF HEMAGGLUTINATING LECTIN WITH ANTICANCER ACTIVITIES FROM PLEUROTUS OSTREATUS

Abstract

Three Pleurotus species were screened for their ability to synthesize mycelial, culture filtrate and fruiting bodies lectins. All tested Pleurotus species were able to synthesize mycelial and fruiting bodies lectins but with different degree of activity, while no extracellular lectin was detected. P. ostreatus Lectin (POL) from its fruiting bodies recorded the highest activity, so it was selected for further studies. Partial sequencing of lectin gene and partial amino acid sequencing were performed, resulting in 267 amino acids. POL purification involved a combination of (NH 4) 2 SO 4 precipitation along with two anion-chromatographic steps using Q-Sepharose column and Mono Q column. POL appeared as a single band with a molecular mass of 29 kDa on SDS-PAGE. Biochemical and biological activities of pure POL were compared with crude extract from the same organism. POL activity was inhibited by xylose with a MIC of 0.1 M. It was active up to 70ºC and pH 11 then its activity completely disappeared. POL activity was inhibited by different concentrations of Hg 2+ , Zn 2+ , Cu 2+ , Mn 2+ , Ca 2+ , Na + and K + ions. POL manifested antibacterial activity, but showed no antifungal activity. It exhibited anticancer activity toward human hepatocellular and colorectal carcinoma with IC 50 of 424 and 270 µg/ml, respectively.