Improved assay system for acidic peptide: N-glycanase (aPNGase) activity in plant extracts.

Plant acidic peptide: N-glycanase (aPNGase) release N-glycans from glycopeptides during the degradation process of glycoproteins in developing or growing plants. We have previously developed a new method to detect the aPNGase activity in crude extracts, which is prerequisite for the construction of aPNGase knockout or overexpression lines. However, this method has the disadvantage of requiring de-sialylation treatment and a lectin chromatography.

Convenient preparation of an antigenic oligosaccharide from white kidney bean powder: A useful plant oligosaccharide for synthesis of immunoactive glycopolymer.

Plant glycoproteins, especially allergenic glycoproteins such as pollen allergens, often carry antigenic N-glycans with α1-3 fucose and/or β1-2 xylose residue(s) on the trimannosyl core structure. We previously reported that one of such antigenic free-form N-glycans, Man3Xyl1Fuc1GlcNAc2 (M3FX) suppressed IL-4 production from Th2 cells of pollinosis patients. For the molecular-level analysis of this immunoactivity, an effective and convenient procedure for large scale preparation of the immunoactive free-form N-glycan and a synthesis of glycopolymers bearing multivalent M3FX has been required.

Novel assay system for acidic Peptide:N-glycanase (aPNGase) activity in crude plant extract.

Acidic peptide:N-glycanase (aPNGase) plays a pivotal role in plant glycoprotein turnover. For the construction of aPNGase-knockout or -overexpressing plants, a new method to detect the activity in crude plant extracts is required because endogenous peptidases present in the extract hamper enzyme assays using fluorescence-labeled N-glycopeptides as a substrate. In this study, we developed a new method for measuring aPNGase activity in crude extracts from plant materials.