Bookshelf

CID-MS/MS spectra of O-glycopeptides (a: m/z: 814.8 [3+]; b: m/z: 936.5 [3+]; c: m/z: 1008.8 [3+]; and d: m/z: 1033.6 [3+]).

In Figure 3a, M is the molecular weight of glycopeptide (2441.0 Da) constituted with LGSEETTEHTPSDASTTEGK (2075.9 Da) of peptide chain and Hex1HexNAc1 (365.1 Da) of glycan moiety, and glycan-linked peptide ions are presented at m/z: 1140.9 (2+) and 761.0 (3+). The distance between m/z: 1140.9 and 1039.4 means that HexNAc unit and their fragments are doubly charged ions. Also, the distance between m/z: 761.0 and 693.4 means that HexNAc unit and their fragments are triply charged ions. m/z: 1039.4 is selected as a parent ion and fragmented with collisional energy on ion trap MS, leading to Figure 4.

In Figure 3b, M is the molecular weight of glycopeptide (2806.2 Da) constituted with LGSEETTEHTPSDASTTEGK (2075.9 Da) of peptide chain and Hex2HexNAc2 (730.3 Da) of glycan moiety, and glycan-linked peptide ions are presented at m/z: 1322.6 (2+), 1222.0 (2+), and 1140.9 (2+) and m/z: 883.0 (3+), 828.7 (3+), and 761.0 (3+), respectively.

In Figure 3c, M is the molecular weight of glycopeptide (3023.6 Da) constituted with LGSEETTEHTPSDASTTEGK (2075.9 Da) of peptide chain and Hex1HexNAc1Neu5Ac1 (947.7 Da) of glycan moiety, and glycan-linked peptide ions are presented at m/z: 1367.5 (2+), 1286.5 (2+), 1221.9 (2+), and 1140.9 (2+) and m/z: 912.3 (3+), 858.2 (3+), 815.1 (3+), and 761.1 (3+).

In Figure 3d, M is the molecular weight of glycopeptide (3097.5 Da) constituted with LGSEETTEHTPSDASTTEGK (2075.9 Da) of peptide chain and Hex2HexNAc2Neu5Ac1 (1021.6 Da) of glycan moiety, and glycan-linked peptide ions are presented at m/z: 1414.5 (2+), 1367.5 (2+), 1323.5 (2+), 1242.4 (2+), 1221.9 (2+), and 1140.9 (2+) and m/z: 937.0 (3+), 882.9 (3+), 828.7 (3+), and 761.1 (3+).