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. 2020 Aug 21;21(17):6038. doi: 10.3390/ijms21176038

Table 3.

Interpretation of ESI-IT mass spectra of [ECA]2–4-core OS glycoforms (fractions 3–5) isolated from E. coli R2 LOS preparation.

Oligosaccharide Structure Calculated Monoisotopic Mass (Da) Observed Ion (m/z) Calculated Ion (m/z) Interpretation
of the Ion
Fraction 3 (negative mode)
[ECA]5 3054.12 nd/1526.06 1017.03/1526.05 [M-3H]3/[M-2H]2
[ECA]5-OAc 3096.13 nd/1547.06 1031.04/1547.06 [M-3H]3/[M-2H]2
[ECA]3-Glc3-GlcNAc-Gal-Hep3-Kdo-P3-Etn 3770.16 1255.69/nd 1255.71/1884.07 [M-3H]3/[M-2H]2
[ECA]3-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn 3850.12 1282.34/nd 1282.37/1924.06 [M-3H]3/[M-2H]2
[ECA]3-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 3893.17 1290.66/nd 1290.71/1936.57 [M-H2O-3H]3/[M-H2O-2H]2
[ECA]3-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 3893.17 1296.69/nd 1296.72/1945.58 [M-3H]3/[M-2H]2
[ECA]3-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 3893.17 1304.03/nd 1304.04/1956.56 [M-3H, Na]3/[M-2H, Na]2
[ECA]3-Glc3-GlcNAc-Gal-Hep3-Kdo-P5-Etn2 3973.13 1323.38/nd 1323.37/1985.56 [M-3H]3/[M-2H]2
[ECA]4-Glc3-GlcNAc-Gal-Hep3-Kdo-P2 4254.37 1417.06/nd 1417.12/2126.18 [M-3H]3/[M-2H]2
[ECA]4-Glc3-GlcNAc-Gal-Hep3-Kdo-P3-Etn 4377.38 1458.08/nd 1458.12/2187.68 [M-3H]3/[M-2H]2
[ECA]4-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 4500.39 1499.07/nd 1499.12/2249.19 [M-3H]3/[M-2H]2
Fraction 4 (negative mode)
[ECA]4 2446.90 nd/1222.44 814.63/1222.44 [M-3H]3/[M-2H]2
[ECA]2-Glc3-GlcNAc-Gal-Hep3-Kdo-P3-Etn 3162.94 1053.30/1580.47 1053.30/1580.46 [M-3H]3/[M-2H]2
[ECA]2-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn 3242.90 1079.66/1620.44 1079.96/1620.44 [M-3H]3/[M-2H]2
[ECA]2-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 3285.94 1094.31/1641.94 1094.31/1641.96 [M-3H]3/[M-2H]2
[ECA]2-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 3285.94 1101.94/1652.91 1101.63/1652.95 [M-3H, Na]3/[M-2H, Na]2
[ECA]2-Glc3-GlcNAc-Gal-Hep3-Kdo-P5-Etn2 3365.91 1120.94/1681.90 1120.96/1681.95 [M-3H]3/[M-2H]2
[ECA]3-Glc3-GlcNAc-Gal-Hep3-Kdo-P3 3727.12 1241.39/nd 1241.36/1862.55 [M-3H]3/[M-2H]2
[ECA]3-Glc3-GlcNAc-Gal-Hep3-Kdo-P3-Etn 3770.16 1255.03/nd 1255.71/1884.07 [M-3H]3/[M-2H]2
[ECA]3-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn 3850.12 1282.38/nd 1282.37/1924.06 [M-3H]3/[M-2H]2
[ECA]3-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 3893.17 1296.67/nd 1296.72/1945.58 [M-3H]3/[M-2H]2
Fraction 5 (negative/positive modes)
Glc3-GlcNAc-Gal-Hep3-Kdo-P3 1905.45 nd/951.73 634.14/951.72 [M-3H]3/[M-2H]2
Glc3-GlcNAc-Gal-Hep3-Kdo-P3-Etn 1948.49 nd/973.27 648.49/973.24 [M-3H]3/[M-2H]2
Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn 2028.46 nd/1004.22 669.14/1004.21 [M-H2O-3H]3/[M-H2O-2H]2
Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn 2028.46 nd/1013.23 675.15/1013.22 [M-3H]3/[M-2H]2
Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 2071.50 nd/1025.73 683.49/1025.73 [M-H2O-3H]3/[M-H2O-2H]2
Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 2071.50 nd/1034.74 689.49/1034.74 [M-3H]3/[M-2H]2
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P3-Etn 2555.71 850.88/1276.83 850.90/1276.85 [M-3H]3/[M-2H]2
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn 2635.68 871.57/1307.82 871.55/1307.82 [M-H2O-3H]3/[M-H2O-2H]2
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn 2635.68 877.63/1316.83 877.55/1316.83 [M-3H]3/[M-2H]2
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 2678.72 885.92/1329.31 885.89/1329.35 [M-H2O-3H]3-/[M-H2O-2H]2
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 2678.72 891.88/1338.31 891.90/1338.35 [M-3H]3/[M-2H]2
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 2678.72 899.25/1349.31 899.22/1349.34 [M−3H, Na]3/[M−2H, Na]2
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P5-Etn2 2758.69 912.56/1369.29 912.55/1369.33 [M-H2O-3H]3/[M-H2O-2H]2
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P5-Etn2 2758.69 918.53/1378.31 918.56/1378.34 [M-3H]3/[M-2H]2
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P5-Etn2 2758.69 925.89/1389.31 925.88/1389.32 [M-3H, Na]3/[M-2H, Na]2
Glc3-GlcNAc-Gal-Hep3-Kdo-P3-Etn 1948.49 nd/975.20 650.50/975.25 [M+3H]3+/[M+2H]2+
Glc3-GlcNAc-Gal-Hep3-Kdo-P3-Etn 1948.49 nd/986.18 657.83/986.24 [M+3H, Na]3+/[M+2H, Na]2+
Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 2071.50 nd/1027.65 685.50/1027.75 [M-H2O+3H]3+/[M-H2O+2H]2+
Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 2071.50 nd/1036.74 691.51/1036.76 [M+3H]3+/[M+2H]2+
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P3-Etn 2555.71 852.88/1278.88 852.91/1278.86 [M+3H]3+/[M+2H]2+
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P3-Etn 2555.71 860.21/1289.84 860.24/1289.85 [M+3H, Na]3+/[M+2H, Na]2+
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P3-Etn 2555.71 nd/1300.75 867.57/1300.85 [M+3H, 2Na]3+/[M+2H, 2Na]2+
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn 2635.68 879.50/1318.75 879.57/1318.85 [M+3H]3+/[M+2H]2+
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 2678.72 887.75/1331.28 887.91/1331.36 [M-H2O+3H]3+/[M-H2O+2H]2+
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 2678.72 893.75/1340.34 893.91/1340.37 [M+3H]3+/[M+2H]2+
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P4-Etn2 2678.72 901.13/1351.34 901.24/1351.35 [M+3H, Na]3+/[M+2H, Na]2+
[ECA]-Glc3-GlcNAc-Gal-Hep3-Kdo-P5-Etn2 2758.69 920.76/1380.33 920.57/1380.35 [M+3H]3+/[M+2H]2+

OAc—O-acetyl group.