Abstract
Cartilage proteoglycan aggregates are separated from collagen and other non-proteoglycan protein by preparative rate zonal sedimentation under associative conditions. Dissociative rate zonal sedimentation produces sedimented proteoglycan of lower protein content with a corresponding increase in the amount of less sedimentable protein-rich proteoglycan. An extensive number of sequential rate zonal sedimentations discloses that the proceess of disaggregation involves the separation of proteoglycans varying continuously in composition with no apparent discontinuities in distribution to indicate the presence of distinctively different macromolecules. The variations encompass proteoglycans of low protein content containing less than 2% keratan sulfate and proteoglycans with keratan sulfate as the predominant polysaccharide (present in concentrations greater than 2-fold that of the chondroitin sulfate) and more than a 10-fold increase in protein content.
Highlights
Cartilage proteoglycan aggregates are separated from collagen and other non-proteoglycan protein by preparative rate zonal sedimentation under associative conditions
Proteoglycans which do not separate from hyaluronic acid in dissociative processes (4) or which do not interact with hyaluronic acid after separation (3) are not necessarily qualitatively different macromolecules
The preparative rate zonal studies on which this report is based have demonstrated that the relative distribution of the proteoglycan macromolecules are markedly influenced by associative and dissociative systems, but there are no indications that the macromolecules are not continuously variable in composition
Summary
An extensive number of sequential rate zonal sedimentations discloses that the process of disaggregation involves the separation of proteoglycans varying continuously in composition with no apparent discontinuities in distribution to indicate the presence of distinctively different macromolecules. The observations with hyaluronic acid (3, 7) conclusively establish that interactions occur with external polyanionic macromolecules excluding the competitive involvement of the massive numbers of anions (both sulfate and carboxyl) within the proteoglycan. This indicates an ordered structure which prevents uncontrollable self-aggregation because of both anionic and cationic interacting sites within the same macromolecules. The preparative rate zonal studies on which this report is based have demonstrated that the relative distribution of the proteoglycan macromolecules are markedly influenced by associative and dissociative systems, but there are no indications that the macromolecules are not continuously variable in composition
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