The chemical constitution of the proteoglycan of human intervertebral disc

Publisher Website
Google Scholar
Abstract
Proteoglycan was prepared from three pools of normal human intervertebral discs by extraction with buffered 4M-guanidinium chloride followed by CsCl-density-gradient ultracentrifugation. Chromatography on agarose (Bio-Gel A-150m) and on DEAE-cellulose suggested a single polydisperse proteoglycan species. The intrinsic viscosities of three preparations were 166, 122 and 168 ml/g. After degradation with 0.5M-KOH containing 0.02M-NaBH4, the glycosaminoglycans were recovered quantitatively and their Ca2+ salts separated into a hexuronate-rich fraction (fraction 1), which was precipitated in 0-45% (v/v) ethanol, and a hexose-rich fraction (fraction2), which was precipitated in 45-70% (v/v) ethanol. Qualitative and quantitative analyses of the glycosaminoglycans revealed fraction 1 to be chondroitin sulphate, and fraction 2 to be keratan sulphate; the latter was contaminated with protein and possibly a small amount of another glycosaminoglycan. For both glycosaminoglycans, plots of log(mol.wt.) against weight fell close to a normal distribution. The mode for chondroitin sulphate was close to 20000; that for keratan sulphate, 10000. A threefold range of molecular weight included the central 16-84% [+/- 1 S.D. of log(mol.wt.)] of the weight of both fractions.