Linkage-specific identification and quantification of sialylated glycans by TIMS-TOF MS through conjugation with metal complexes

Mass spectrometry is an indispensable technology for the characterization of glycans. However, specific identification of isomeric glycans especially sialylated glycan isomers using mass spectrometry alone is challenging, which is why orthogonal techniques are needed. Aiming to achieve simple, rapid, and specific identification of sialyl-linkage isomers, we reported herein a trapped ion mobility spectrometry time of flight mass spectrometry (TIMS-TOF MS) method for linkage-specific identification of sialylated glycans through conjugation with metal complexes. Two pairs of sialyl-linkage isomers including 3'/6′-sialyllactose (3'/6′-SL) and 3'/6′-sialyl-N-acetyllactosamine (3'/6′-SLN) conjugated with the diethylenetriamine (DETA) or 2,2′; 6′,2″-terpyridine (Terpy) ligand and transition metal ion (Mn2+, Fe2+, Co2+, Ni2+, Cu2+, or Zn2+) were studied by TIMS-TOF MS. The two pairs of sialylated isomers were successfully separated with a metal-ligand system, and relative quantification of sialyl-linkage isomers was demonstrated. In addition, the linkage of the sialic acid moiety can also be distinguished with MS/MS in combination with the metal-ligand system. [Display omitted] •A simple and rapid TIMS-TOF MS method for sialylated glycan isomers is reported.•Baseline separation of two pairs of glycans is achieved with ternary complexes.•Relative quantification of sialyl-linkage isomers was demonstrated.•α2,6 and α2,3 linked glycan conjugated with Cu-DETA shows fragmentation differences.