Isomeric Effects in Collisionally-induced Dissociation of β-(1→6)-linked Cyclic Tetrasaccharides of the Glc p 2 Glc pN 2 Composition

Electrospray ionization (ESI) high resolution mass spectra of positively charged ions (the first and the second order) of protonated molecules of isomeric β-(1→6)-linked cyclic tetrasaccharides of the Glcp2GlcpN2 composition were recorded and interpret. It was shown that the second-order mass spectra of these compounds have some differences reflecting the mutual positions of the glucopyranose and glucosamine residues. The most significant qualitative differences were observed for MS/MS spectra of doubly protonated, doubly charged molecules.