Apolipoprotein H is not affected by in vitro glycosylation

Increased nonenzymatic glycosylation of all major classes of apolipoprotein s has been demonstrated in diabetes. In this work we deal with the in vitro nonenzymatic glycosylation of apolipoprotein H, whose role in lipid metabo lism is still poorly understood and whose levels increase in diabetes. Apol ipoprotein Il was isolated from human plasma and purified through a combina tion of affinity chromatography and continuous elution electrophoresis. The in vitro glycosylation was performed by incubating purified apolipoprotein H with high concentration of glucose. Our results indicate that the in vit ro nonenzymatic glycosylation has no effect on the physical properties of a polipoprotein H, despite the fact that this apolipoprotein contains a high number of lysine residues. Since the in vitro concentration of glucose was far higher than the levels normally found in diabetic subjects, it is unlik ely for apolipoprotein H to become glycosylated in diabetes.