Identification of glycoproteins in human cerebrospinal fluid

Human cerebrospinal fluid (CSF), which circulates within the ventricles of the brain and the subarachnoid space of the central nervous system (CNS), is an excellent source for proteomic discovery of biomarkers in neurodegenerative disorders, including Alzheimer's and Parkinson's disease. Protein glycosylation is an abundant and biologically significant posttranslational modification. Glycoproteins, commonly associated with membrane and secreted proteins, are highly enriched in body fluids, including CSF. Focusing on glycoproteins also improves the dynamic range of proteomic profiling of the CSF, where low abundance proteins are difficult to identify because of the CSF's enormous complexity. As an ongoing process to define the human CSF proteome, we have recently employed a complementary proteomic approach, with integrated lectin affinity column and hydrazide chemistry, for CSF glycoprotein identification. This investigation has revealed many proteins of low abundance that are related to the CNS structurally and/or functionally. This review centers on the technical details involved in various steps in sample preparation as well as proteomic analysis of CSF glycoproteins.