Purification and partial characterization of a novel anti-tumor glycoprotein from cultured mycelia of Grifola frondosa

A novel glycoprotein GFG-3a with the molecular weight of 88.01 kDa and potent anti-tumor activity was isolated from the cultured mycelia of Grifola frondosa GF9801. GFG-3a was heat-sensitive with the decreasing anti-proliferative activity after treated from 56 degrees C to 100 degrees C for 10-120 min. GFG-3a was a glycoprotein with O-glycosylation and contained 6.20% carbohydrate composed of D-arabinose, D-fructose, D-mannose, and D-glucose with a molar ratio of 1.33:4.51:2.46:1.00. FT-IR and NMR spectra proved that GFG-3a contained protein and carbohydrate portions with 3-O-methyl-galactose residues, (1 -> 4)-linked beta-galactose residues, and beta-linked glucose residues. Circular dichroism (CD) revealed that GFG-3a was a predominantly beta-sheet glycoprotein with a relatively small alpha-helical content. Protein sequencing and 3D model of GFG-3a were finally predicted by using MALDI-TOF-MS, NCBI blast search and online SWISS-MODLE Workspace service. Our findings will be a reference for the further structure-activity relationship analysis of the mushroom glycoproteins. (C) 2013 Elsevier B.V. All rights reserved.