Comparison of N-linked glycosylation of protein C in newborns and adults

Protein C (PC) is a major anticoagulant that stems the propagation of thrombin. The activated form of PC (APC), in association with the cofactor protein S, proteolytically converts activated coagulation factors VIIIa and Va into inactive forms. Studies have shown that forms of PC that contain 3N-linked glycans (beta-PC) are functionally distinct from the fully glycosylated 4-glycan type (alpha-PC). Since some findings have also hinted at qualitative differences in PC from newborns and adults, we decided to determine the relative constitution of glycoforms in these age groups. Subtypes of PC in newborn and adult plasmas were distinguished by SDS polyacrylamide electrophoresis and Western blotting, followed by immunological analysis. Newborns were found to have alpha-PC/beta-PC mole ratios of 8.8:1, compared to 2.3:1 in adults. PC was also isolated by immunoaffinity chromatography from newborn and adult plasmas. Glycans were released by protease treatment and studied by mass spectrometry. Results from glycan analysis showed a small range of glycan structures in both age groups. No clear differences were noted between newborn and adult PC microheterogeneity in glycan structures (branching). We conclude that newborns have important differences in PC macroheterogeneity in glycoform content relative to adults. This age-dependent glycosylation variation may have implications in management of PC function in vivo.