| May 08, 2023 |
Using nanopore single-molecule sensing to identify glycans
(Nanowerk News) Glycans play diverse and critical roles in numerous cellular activities, but their highly complex structures make their analysis a challenge. These structures arise from differences in composition, branching, regio- and stereochemistry, and modification, resulting in unparalleled structural diversity.
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Recently, a joint research team led by Prof. Qing Guangyan and Prof. Liang Xinmiao from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) developed a glycan identification method utilizing nanopore single-molecule sensing and a glycan derivatization strategy.
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The study was published in Nature Communications ("Identification of tagged glycans with a protein nanopore").
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While the potential of identifying and sequencing glycans using nanopore single-molecule techniques has generated interest, there has been limited progress in the past decade. Only a few studies have focused on high molecular weight polysaccharides or certain monosaccharides. Smaller, more structurally diverse glycans with greater biological significance have not been detected using single-molecule nanopore methods, primarily due to their fast passage through the nanopore, small size, and weak affinity.
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To overcome this challenge, the researchers introduced a derivatization strategy that linked an aromatic-type tag group to small glycans using a highly efficient and straightforward reductive amination reaction. The tagged glycans were then sensed with a wild-type aerolysin nanopore, producing strong nanopore blockage signals.
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By processing the nanopore single-molecule blockage events, the researchers obtained a scatter plot based on blockage current and dwell time, which served as a fingerprint map. This allowed them to identify different glycan isomers, glycans of varying lengths, and branched simple glycans. They also discovered that multiple cation-π interactions between the aromatic tag of the glycan and the K238 residues of the nanopore interface slowed the translocation of the tagged glycan, contributing to its sensing.
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"This study expands the boundaries of nanopore sensing beyond its traditional focus on nucleic acids and proteins and harnesses its potential in the glycomics and glycoscience field, which may pave the way towards nanopore glycan sequencing," said Prof. Qing.
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