Human cartilage proteoglycans isolated from normally ossifying and congenitally malformed leg bones.

Proteoglycans were extracted with 4 M guanidine HCl solution containing protease inhibitors from various zones of human epiphyseal cartilages of the normally ossifying fibula and cartilaginous rudiment of the tibia of a 12-month-old boy with congenital absence of the tibia, when the knee disarticulation was performed. All the proteoglycan preparations from the epiphyseal cartilages were separated with a sucrose density gradient centrifugation into two components: a heavy, major component and a light one. The molecular size and the proportion of isomeric chondroitin sulfates of polysaccharides of the heavy component differed from those of the light one. The relative amounts of isomeric chondroitin sulfates in the polysacharide moieties of the components also varied among these zones. The glycosaminoglycan content in the rudimentary tibia was equal to that of the epiphyseal cartilage of the fibula. However, proteoglycan preparations showed neither the normal sedimentation profile with two peaks nor the zonal differences as to the proportion of isomeric chondroitin sulfates. These results suggest that the alterations in proteoglycan metabolism might be involved in the pathogenetic mechanisms producing the congenital limb defect.