Proteinpolysaccharide Complex from Bovine Nasal Cartilage: A Comparison of low and high shear extraction procedures

Abstract

Two procedures for isolating 80 to 85% of the total hexuronic acid from bovine nasal cartilage as proteinpolysaccharide complex are described and compared. The first method, termed disruptive, extracts the complex by exhaustive high speed homogenization of the tissue in salt solutions of low ionic strength; proteinpolysaccharides used in most previous investigations were extracted similarly. The preparation is then purified by precipitation as the cetylpyridinium salt. The second method, termed dissociative, avoids shear by extracting proteinpolysaccharides into solvents containing optimal concentrations of various electrolytes and then utilizes equilibrium density gradient sedimentation to remove glycoprotein and soluble collagen. The effects of pH, temperature, and nature and concentration of electrolyte on the efficiency of dissociative extraction are presented; of the parameters investigated, only the type and concentration of electrolyte appear to be critical. Although both procedures yield products which exhibit bimodal distributions of sedimentation coefficients in the ultracentrifuge, the disruptive method denatures the macromolecules and decreases their average sedimentation coefficients. The faster sedimenting mode reversibly disaggregates under dissociative extraction conditions, suggesting that disaggregation is fundamental to the extraction process. Aggregation appears to be effected through strong ionic interactions; however, reduction and alkylation of cystine residues prevents reaggregation, suggesting that the interaction also depends on the conformation of protein moieties of the macromolecules.