Determination of urinary oligosaccharides by high-performance liquid chromatography/electrospray ionization-tandem mass spectrometry: Application to Hunter syndrome

The reaction of heparan sulfate (HS) and dermatan sulfate (DS) oligosaccharides with 1-phenyl-3-methyl-5-pyrazolone (PMP) yields hydrophobic derivatives that are amenable to separation by reversed-phase high-performance liquid chromatography (RP-HPLC) and analysis by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). We describe here the development of an RP-HPLC-ESI-MS/MS assay for the measurement of di- to pentasaccharides derived from HS and DS in the urine of mucopolysaccharidosis (MPS) type II patients, as PMP derivatives. HPLC separation was performed on a 3-mum Alltima C18-LL column (50 x 2.1mm) using a gradient elution of up to 25% acetonitrile over 17 min, and an API-4000 mass spectrometer equipped with a turbo-ion-spray source was used in the negative ion multiple reaction monitoring mode for PMP-oligosaccharide determination. Using this method, we found that the derivatization kinetics of the oligosaccharides was influenced by the type of residue present at the reducing end (i.e., N-acetylglucosamine, N-acetylgalactosamine, or uronic acid). The elevation of each of the measured oligosaccharides in MPS II urine enabled complete discrimination of a cohort of MPS II patient urines from unaffected controls. This assay is rapid and reproducible and may be useful for the diagnosis of MPS II, and also for monitoring of disease progression and efficacy of therapy.