Proteoglycans of bovine cementum: isolation and characterization

The proteoglycans associated with the mineralized matrix of bovine cementum have been studied biochemically and their distribution within this tissue localized immunohistochemically. Both hyaluronate and proteoglycans were fractionated by DEAE-Sephacel ion-exchange chromatography. The proteoglycans eluted in three separate peaks of which two contained alkali labile protein associated with glycosaminoglycans, and one appeared as free glycosaminoglycan chains. Analysis of the glycosaminoglycans identified chondroitin sulfate as the predominant species, although minor quantities of dermatan sulfate and heparan sulfate were also identified. Agarose-acrylamide gel electrophoresis and Sepharose CL-6B molecular sieve chromatography of the proteoglycans indicated them to be smaller in size with respect to periodontal ligament and gingival proteoglycans, but similar to bone and dentine proteoglycans. Amino acid analyses indicated subtle differences between cementum and bone proteoglycans. Using a monoclonal antibody (9-A-2) which recognizes the unsaturated disaccharide of chondroitinase ACII-digested glycosaminoglycans, chondroitin sulfate was identified in the pericellular environment within the lacunae housing the cementoblasts as well as in the extracellular matrix of cementum.