Application of ion mobility tandem mass spectrometry to compositional and structural analysis of glycopeptides extracted from the urine of a patient diagnosed with Schindler disease

Rapid Commun Mass Spectrom. 2015 Nov 15;29(21):1929-37. doi: 10.1002/rcm.7288.


Rationale: Schindler disease is caused by the deficient activity of α-N-acetylgalactosaminidase, which leads to an abnormal accumulation of O-glycopeptides in tissues and body fluids. In this work the Schindler condition is for the first time approached by ion mobility (IMS) tandem mass spectrometry (MS/MS), for determining urine glycopeptide fingerprints and discriminate isomeric structures.

Methods: IMS-MS experiments were conducted on a Synapt G2s mass spectrometer operating in negative ion mode. A glycopeptide mixture extracted from the urine of a patient suffering from Schindler disease was dissolved in methanol and infused into the mass spectrometer by electrospray ionization using a syringe-pump system. MS/MS was performed by collision-induced dissociation (CID) at low energies, after mobility separation in the transfer cell. Data acquisition and processing were performed using MassLynx and Waters Driftscope software.

Results: IMS-MS data indicated that the attachment of one or two amino acids to the carbohydrate backbone has a minimal influence on the molecule conformation, which limits the discrimination of the free oligosaccharides from the glycosylated amino acids and dipeptides. The structural analysis by CID MS/MS in combination with IMS-MS of species exhibiting the same m/z but different configurations demonstrated for the first time the presence of positional isomers for some of the Schindler disease biomarker candidates.

Conclusions: The IMS-MS and CID MS/MS platform was for the first time optimized and applied to Schindler disease glycourinome. By this approach the separation and characterization of Neu5Ac positional isomers was possible. IMS CID MS/MS showed the ability to determine the type of the glycopeptide isomers from a series of possible candidates.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Child, Preschool
  • Glycopeptides / chemistry*
  • Glycopeptides / urine*
  • Humans
  • Isomerism
  • Lysosomal Storage Diseases / urine*
  • Male
  • Neuroaxonal Dystrophies / urine*
  • Tandem Mass Spectrometry / methods*
  • alpha-N-Acetylgalactosaminidase / deficiency*
  • alpha-N-Acetylgalactosaminidase / urine


  • Glycopeptides
  • alpha-N-Acetylgalactosaminidase

Supplementary concepts

  • Schindler Disease, Type I