Poplar catkin: A natural biomaterial for highly specific and efficient enrichment of sialoglycopeptides

Sialic acids as terminal entities of larger glycans linked to proteins and lipids are involved in multiple different pathological and physiological processes. Structural characterisation of sialoglycoconjugates is required to understand their biological function. However, a comprehensive sialylation analysis of sialoglycoconjugates has remained challenges. In this study, we employ a natural biomaterial, poplar catkin derived from white poplar tree (Populus tomentosa Carr.), to develop a novel capturing microtip for selective and efficient enrichment of sialoglycopeptides, without losses of sialic acid residues and water molecules from sialoglycopeptides. Scanning electron microscopy and Fourier-transform infrared spectroscopy analysis, along with Mäule and Wiesner staining assays, indicated that the main components on the outer layer of the poplar catkin are syringyl and guaiacyl lignins which play a key role in enriching sialoglycopeptides from complex peptide mixture.