Isolation and Partial Characterization of a Glycoprotein from Bovine Cortical Bone

Abstract

1 A fraction (G2) which contained 30% of the total non-collagenous proteins was prepared from neutral EDTA extracts of bovine cortical bone. Three hitherto undescribed proteins (G2B-glycoprotein, GZC-glycoprotein, G2CF) were identified in this fraction together with collagen, serum albumin, immunoglobulin G and transferrin. 2 The G2B-glycoprotein was prepared from the G2 fraction and shown to be homogenous by electrophoretic and immunochemical criteria. 3 The G2B-glycoprotein was demonstrated to be present in bovine plasma at a concentration of approximately 20 mg/100 ml. It was found that in the collagenase digest of decalcified bone matrix the ratio of the G2B-glycoprotein concentration to the serum albumin or immunoglobin G concentration was upto 250 times higher than the ratio in plasma. 4 The G2B-glycoprotein contained approximately 78% protein, 4% sialic acids, 3 hexosamines and 14% neutral sugars, and had an apparent molecular weight of around 50000.