Many cellular processes depend on glycans for a variety of important functions. Glycans play a variety of functions, and their complex structures, which are the result of variations in composition, branching, region- and stereochemistry, and modifications, are well suited. The structural characterization of glycans is made challenging by this unparalleled structural variation.
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Recently, a collaborative research team from the Dalian Institute of Chemical Physics (DICP) from Chinese Academy of Sciences (CAS), under the direction of Prof. Guangyan Qing and Prof. Xinmiao Liang, developed a glycan identification method based on single-molecule nanopore sensing through a glycan derivatization strategy.
The study was released on March 28th2023 in Nature Communications.
Potential interest has been generated by the identification and sequencing of glycans using the nanoporous single molecule method. Over the previous twelve years, it had made little progress. Only a few examples concentrated in certain monosaccharides or high molecular weight polysaccharides are described.
Single molecule detection with nanopores has not been performed for smaller but structurally more varied glycans with greater biological importance. This is partly because the fast pathway of glycans through the nanopores cannot be sensed due to their small size and weak affinity of glycans with the nanopores.
The researchers developed a derivatization technique to overcome this problem by attaching small glycans to groups of aromatic-type tags via a fast and simple reductive amination process. The wild-type aerolysin nanopore recognizes tagged glycans by displaying a strong nanopore occlusion signal.
Processing of single molecule nanopore blockage events led to generation of scatter plots based on blockage currents and residence duration as a fingerprint map. They found many isomers of glycans as well as simple branched glycans and glycans of various lengths.
The team found that the aromatic tags on the glycans had some π-cation interactions with K238 residues at the nanopore interface, which slowed translocation of tagged glycans and aided sensing.
This study pushes the boundaries of nanopore sensing beyond its traditional focus on nucleic acids and proteins, and activates its strengths in the fields of glycomics and glycanscience, possibly paving the way towards nanopore glycan sequencing.
Guangyan Qing, Professor, Dalian Institute of Chemical Physics, Chinese Academy of Sciences
Li, M., et al. (2023) Identification of glycans tagged with protein nanopores. Nature Communications. doi:10.1038/s41467-023-37348-5.