Structural Characterization of N-Glycans of Cauxin by MALDI-TOF Mass Spectrometry and Nano LC-ESI-Mass Spectrometry

Abstract

Cauxin is a carboxylesterase-like glycoprotein excreted as a major component of cat urine. Cauxin contains four putative N-glycosylation sites. We characterized the structure of an N-linked oligosaccharide of cauxin using nano liquid chromatography (LC)-electrospray ionization (ESI) and matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MALDI-QIT-TOF MS) and MS/MS, and high-performance liquid chromatography (HPLC) with an octadecylsilica (ODS) column. The structure of the N-linked oligosaccharide of cauxin attached to ⁸³Asn was a bisecting complex type, Galβ1-4GlcNAcβ1-2Manα1-3(Galβ1-4GlcNAcβ1-2Manα1-6)(GlcNAcβ1-4)Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc.