Screening of a unique lectin from 16 cultivable mushrooms with hybrid glycoprotein and neoproteoglycan probes and purification of a novel N-acetylglucosamine-specific lectin from Oudemansiella platyphylla fruiting body

Hybrid glycoprotein and neoproteoglycan probes were prepared by coupling various glycoproteins or polysaccharides to peroxidase or biotinyl bovine serum albumin, respectively. Lectins recognizable by the neoglycoconjugate probes were extracted from 16 cultivable mushrooms. Dot-blot assay revealed five extracts to be reactive with only hybrid glycoprotein probes, but others also reacted with neoproteoglycan probes. According to the reactivity pattern with probe screening, the one lectin from Oudemansiella platyphylla extract (OPL) bound best with asialotransferrin-- and asialoagalactotransferrin--peroxidase probes and was isolated using an asialotransferrin column, but it did not bind with other hybrid glycoprotein or neoproteoglycan probes. OPL, consisting of two polypeptides with high homology in the N-terminal amino acid sequences, exhibited weak hemagglutinating activity. Purified OPL specifically bound the beta-GlcNAc probe among various biotinylated polymeric sugar probes, while it exhibited essentially the same binding specificity toward neoglycoconjugate probes as that of the crude extract, showing a preference for the asialobiantennary complex type of N-linked glycans. These results indicate that the neoglycoconjugate probes are valuable in lectin screening.