Large-scale purification and characterization of non-glycosylated Gc globulin (vitamin D-binding protein) from plasma fraction IV.

Gc globulin, also called vitamin D-binding protein, is a plasma protein involved in the extracellular actin-scavenger system. Low levels of Gc globulin have been found to correlate with multiple organ failure and nonsurvival of patients with fulminant hepatic failure and trauma. Therefore substitution therapy with Gc globulin might be beneficial for such patients, increasing their chance of survival. In the present study, we describe a large-scale purification process for the production of a virus-safe human plasma-derived Gc globulin from Cohn fraction IV paste. The process includes three ion-exchange-chromatography steps, followed by a gel filtration, and two virus-reduction steps are implemented. The Gc globulin product was characterized with respect to purity, functional activity, glycosylation and, finally, with respect to content of endotoxin. From the results, it can be concluded that human Gc globulin purified from Cohn fraction IV is non-glycosylated. The purified Gc globulin is able to mask the presence of endotoxin by 20%.