HETEROGENEITY OF ALPHA(1)-ACID GLYCOPROTEIN IN RHEUMATOID-ARTHRITIS

alpha(1)-Acid glycoprotein (AGP) or orosomucoid is a major serum glyco protein, of unknown physiological function, which is classified as one of the positive acute phase reactants since its plasma concentration becomes elevated two-to five-fold in certain disease states. Additiona lly, the proportions and identities of the five asparaginyl-linked com plex oligosaccharide chains are altered during several physiological a nd pathological conditions, which may be functionally significant. The key to studying the structural heterogeneity of AGP is to develop a p rocedure that will isolate AGP without structural degradation. We have developed a method for the purification of AGP, using procedures unli kely to damage the glycoprotein structure, which was utilised to isola te AGP from samples of normal and rheumatoid plasma. The effectiveness of the purification procedure was examined by enzymatically deglycosy lating each sample of AGP and separating the released oligosaccharides by chromatography on a pellicular high-performance anion-exchange (HP AE) resin at pH 13. The analytical profile for normal AGP was consiste nt with that previously reported thus indicating that the purification procedure did not denature the oligosaccharide chains of AGP. Additio nally, there was a noticeable difference between the profiles for AGP from normal and rheumatoid plasma.