US 12,474,308 B2
Method to identify the glycosidic linkage of sialic acid in glycopeptides
Suya Liu, Woodbridge (CA); and Takashi Baba, Richmond Hill (CA)
Assigned to DH TECHNOLOGIES DEVELOPMENT PTE. LTD., Singapore (SG)
Appl. No. 18/002,533
Filed by DH TECHNOLOGIES DEVELOPMENT PTE. LTD., Singapore (SG)
PCT Filed Jul. 6, 2021, PCT No. PCT/IB2021/056054
§ 371(c)(1), (2) Date Dec. 20, 2022,
PCT Pub. No. WO2022/009095, PCT Pub. Date Jan. 13, 2022.
Claims priority of provisional application 63/049,157, filed on Jul. 8, 2020.
Prior Publication US 2023/0251231 A1, Aug. 10, 2023
Int. Cl. G01N 30/72 (2006.01); G01N 30/02 (2006.01); G01N 30/88 (2006.01); G01N 30/96 (2006.01); G01N 33/68 (2006.01); H01J 49/00 (2006.01); H01J 49/42 (2006.01)
CPC G01N 30/72 (2013.01) [G01N 30/88 (2013.01); G01N 30/96 (2013.01); G01N 33/6848 (2013.01); G01N 2030/022 (2013.01)] 23 Claims
OG exemplary drawing
 
1. A system for identifying one or more linkages of a sialic acid (SA) to a glycan of an isomer of a glycopeptide using electron capture dissociation (ECD) and multiple reaction monitoring (MRM) precursor ion to product ion transitions, comprising:
a separation device that separates one or more isomers of a glycopeptide from a sample;
an ion source that ionizes the one or more separated isomers, producing an ion beam that includes isomer ions of a precursor ion of the glycopeptide;
a tandem mass spectrometer that, for each separation time of a plurality separation times, using an ECD device with 2-5 eV electrons, executes on the ion beam a first group of one or more MRM transitions that each includes the precursor ion and a product ion known to be enhanced or suppressed for a first linkage of an SA of the glycopeptide to a glycan of the glycopeptide and a second group of one or more MRM transitions that each includes the precursor ion and a product ion known to be enhanced or suppressed for a second linkage for the SA to the glycan, producing an extracted ion chromatogram (XIC) for the precursor ion and an XIC for each product ion of the first and second groups; and
a processor in communication with the tandem mass spectrometer that
a. calculates a separation time of an isomer of the one or more separated isomers from a peak of the XIC,
b. sums product ion intensities of the first group at the separation time producing a first sum and sums product ion intensities of the second group at the separation time producing a second sum using XICs of the first and second groups,
c. calculates a ratio of the first sum to the second sum,
d. compares the ratio at the separation time to predetermined ratio ranges that each corresponds to a combination of a selection from a set of the first linkage and the second linkage taken one or more times, wherein one or more times correspond to one or more SAs known to be included in the glycopeptide, and
e. identifies one or more linkages of the SA to the glycan of the isomer from a combination found to match the ratio in the comparison.