Proteomic-Based Techniques for the Qualitative and Quantitative Characterisation of Food Lectins: The Common Bean’s Case Study

Simple and rapid protocols based on low-resolution mass spectrometry were developed for the qualitative and quantitative characterisation of bean (Phaseolus vulgaris) lectins at the molecular level. Protein glycosylation was studied using on-column enrichment of glycopeptides followed by permethylation of N-glycans. An affinity column equipped with the α-1-acid glycoprotein (AGP or AAG) was prepared for the selective isolation of active lectins and subsequent HPLC-based quantification. Mass spectrometry-based glyco(proteomic) analysis protocols were applied for the structural characterisation. The method developed on a commercial standard of phytohemagglutinin (PHA-P) is presented here with case studies applied to unfractionated bean flours.