Capillary electrophoresis-based separation of transferrin sialoforms in patients with carbohydrate-deficient glycoprotein syndrome

The heterogeneity associated with protein glycoforms has been a challenge to analytical chemists and the subject of structure-function studies for biochemists since their presence in biological systems had been confirmed some three decades ago. Initial investigations led to discoveries of synthetic and degradative pathways, and brief forays into functional determination of the ''glyco'' portion on the protein activity in glycoproteins. Only recently has it come to our understanding that variations from the ''normal'' glycosylation patterns might be indicative of pathological states. The presence of certain transferrin (Tf) glycoforms in human serum has been shown to correlate with certain clinical syndromes. Hence, the ability to separate and quantitatively measure the various forms of human Tf has become increasingly important. It this study, we demonstrate that a simple method utilizing a DB-17-coated capillary to slow endoosmotic flow and a sieving buffer containing hydroxyethyl cellulose allows for the resolution of sialoforms of transferrin. An analysis time of less than eight minutes allows for baseline resolution of the lower sialoforms of Tf, presenting a simple, rapid test for carbohydrate-deficient transferrin (CDT). We demonstrate the utility of this methodology for the facile diagnosis of carbohydrate-deficient glycoprotein syndrome, and postulate that it may allow for the detection of other carbohydrate-deficient protein-related disease states.