Characterization of Mannose-6-Phosphate in Lysosomal Enzymes by Tandem Mass Spectrometry

摘要

The lack of enzymes to metabolize macromolecules in the lysosomes leads to lysosomal storage diseases (LSD) where the non-metabolized macromolecules build up in the lysosomes and may result in cell stress and cell death accompanied by tissue distress and organ failure. Some of the well known LSDs are Fabry disease, Hunter syndrome and Gaucher disease, for which enzyme replacement therapy (ERT) provides an effective treatment. These enzymes are glycoproteins, where glycosylation plays important functional roles. The glycans of lysosomal enzymes are not structurally well characterized because not all are commercially available in an adequate amount and/or quality. Moreover, the traditional approach to analyzing these glycans utilizes lengthy chromatographic methods. Here, MALDI-TOFMS is utilized for a rapid glycan fingerprinting of a lysosomal enzyme followed by ESI-MS/MS for structural details of the identified glycans. The focus of this poster is on characterization of phosphorylated mannose (Man-6-P) containing glycans, which is required for cellular uptake and transport of the administered enzyme to the lysosomal site of action.