Isolation and characterization of two proteoglycans from bovine tendon

Proteoglycans were extracted from bovine flexor digitorum profundus tendon (FDP) with 4 M-guanidine hydrochloride in the presence of proteinase inhibitors and purified by density-gradient centrifugation and ion-exchange chromatography. Tendon proteoglycans were fractionated into two major components, D1 and D2, and characterized by chemical analysis and enzymatic (chondroitinases and hyaluronidase) degradations. The two proteoglycans differ with respect to the structure of their glycan side chains; D1 chains were mainly chondroitinsulfate, whereas D2 contained 40% of dermatansulfate. In both proteoglycans keratansulfate chains are probably present. Tendon proteochondroitinsulfate was of larger size than proteodermatansulfate as judged by gel-chromatography on Sepharose 2B. Proteoglycan-collagen interactions were studied by affinity-chromatography on Sepharose 4B-collagen. Both proteochondroitinsulfate and proteodermatansulfate were resolved in two components, with different affinity for collagen. In proteodermatansulfate the component at higher affinity was predominant.