High Abundance of Unusual High Mannose N-Glycans Found in Beans

High mannose N-glycans extracted from eight different beans (black bean, soybean, pea, white kidney bean, pinto bean, mung bean, white hyacinth bean, and red bean) were studied using the state-of-the-art mass spectrometry method logically derived sequence tandem mass spectrometry (LODES/MSⁿ). These beans show very similar N-glycan isomer profiles: one isomer of Man₉GlcNAc₂ and Man₈GlcNAc₂, two isomers of Man₇GlcNAc₂, three isomers of Man₆GlcNAc₂, and five isomers of Man₅GlcNAc₂ were found. Isomers not predicted by current N-glycan biosynthetic pathways were found in all beans, indicating the possibility of alternative biosynthetic pathways in these plants. The high abundance of unusual high mannose Man₅GlcNAc₂ N-glycans in beans is particularly useful for the large-scale preparation of high mannose N-glycans that are not easily found in the other biological systems.