Plasma and Serum Glycoproteins

The sera of certain animal species contain substances which are not antibodies, although they bind to hepatitis B surface antigen. They are probably glycoproteins and can be selectively removed from sera by reaction with purified hepatitis B surface antigen. 

A heterogeneous population of serum glycoproteins, which bind to immobilized Ricinus communis lectin, have been isolated and shown to account for the inhibition of the binding of desialylized glycoprotein to the hepatocyte membrane.These glycoproteins are present in small amounts in normal human serum, but in increased levels in serum from patients with cirrhosis. 

The major proelastase 2 binding factor in human plasma is Oj-protease inhibitor.Proelastase 2 reacts directly with the inhibitor via a partial active site in a manner similar to that of endo-peptidases. 

Guinea-pig tti-microglobulin, isolated from plasma or urine, is homologous to human Oii-microglobulin, on the basis of molecular weight, carbohydrate composition, and cross-reaction with antisera.  

Traces of concanavalin A have been detected in samples of purified aj-anti-trypsin after affinity chromatography on immobilized concanavalin A. The interfering lectin may be removed by adsorption of the Oj-antitrypsin on thiol-activated macroporous agarose. 

---