"Internal residue loss": rearrangements occurring during the fragmentation of carbohydrates derivatized at the reducing terminus.
Rearrangement reactions involving migration of fucose and, occasionally, other residues have been found in the CID spectra of [M + H]+ and [M + 2H]2+ ions, but not [M + Na]+ ions, generated from several O-linked carbohydrates and milk sugars derivatized at their reducing termini with aromatic amines such as 2-aminobenzamide. Such rearrangements, which are similar to those reported by other investigators from several underivatized carbohydrates and glycosides, cause an apparent loss of sugar residues from within a carbohydrate chain and can produce ambiguous results during spectral interpretation. A mechanism, involving initial protonation of the amine nitrogen atom of the derivative, is proposed to account for the formation of the observed ions.
Harvey
David J
DJ
Oxford Glycobiology Institute, Department of Biochemistry, UK. dh@glycob.ox.ac.uk
Mattu
Taj S
TS
Wormald
Mark R
MR
Royle
Louise
L
Dwek
Raymond A
RA
Rudd
Pauline M
PM
D000588:Amines / Q000737:chemistry; D000818:Animals; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000737:chemistry*; D005643:Fucose / Q000032:analysis; D008892:Milk / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D021241:Spectrometry, Mass, Electrospray Ionization
D000588:Amines; D002241:Carbohydrates; D005643:Fucose