Proteoglycans of fetal bovine tendon.

The proteoglycans (PG) of bovine fetal tendon (4-8 months in utero) were extracted with 4 M guanidine HCl and partially purified by ion exchange chromatography. Proteoglycans from fetal tendon were virtually entirely small molecules (Kav approximately equal to 0.55 by Sepharose CL-4B chromatography). These small proteoglycans had dermatan sulfate glycosaminoglycan chains and a core protein (after chondroitinase ABC digestion) with Mr approximately equal to 45,000 on sodium dodecyl sulfate-polyacrylamide gels. By electrophoretic mobility, immunocross-reactivity, and V8 protease sensitivity, these proteoglycans were determined to be of both PG I and PG II types. In contrast, adult tendon contains only the PG II type of small proteoglycan. Proteoglycans synthesized by fetal tendon explant cultures were, by both chromatographic and electrophoretic mobilities, somewhat larger than those extracted from the same tissue. There was no difference in the spectrum of proteoglycans observed between those regions of fetal tendon destined to receive only tensional forces (proximal) and those regions that will be subjected as well to compressive forces (distal) in the adult. These observations indicate that the proteoglycan content and synthetic capability of all regions of fetal tendon are constant and significantly different from those of both the tensional and fibrocartilaginous regions of adult tendon.