Plasma proteins in human cortical bone: Enrichment ofα 2 HS-glycoprotein,α 1 acid-glycoprotein,and IgE

Summary Human cortical bones were extracted with EDTA, and the residue after EDTA extraction was digested with bacterial collagenase. Ten plasma proteins were identified and quantitated in the EDTA extracts. Three of them—IgE, IgD, andα ₁acid-glycoprotein—had not previously been described in bone or dentine. Five plasma proteins identified in collagenase digests are albumin, IgG, IgA, IgE, andα ₁acid-glycoprotein. IgE,α ₁acid-glycoprotein, andα ₂HS-glycoprotein were found to be concentrated in the bone more than other plasma proteins by factors between 11 and 525. The identification of plasma proteins was facilitated by the addition of polyethylene glycol in agarose gel. The presence of plasma proteins both in EDTA extracts and in collagenase digests suggests their structural role in bone.