The isolation of collagen-associated proteoglycan from bovine nasal cartilage and its preferential interaction with α2 chains of type I collagen

摘要

pA collagen complex from bovine nasal cartilage was prepared by extraction of the tissue with 3M-MgClsub2/sub solutions, by using two different procedures. When it was compared with calf skin acid-soluble tropocollagen by polyacrylamide-gel electrophoresis, the 3M-MgClsub2/sub-soluble cartilage collagen in the complex appeared to be predominantly type I in nature, consisting of both αsub1/sub and αsub2/sub chains. The soluble cartilage collagens were digested with purified bacterial collagenase, and the soluble digests were fractionated on Sepharose 4B. Hydroxyproline-free proteoglycan was isolated in the excluded volume of the column eluate, and this was found to be an aggregate which could be dissociated to link proteins and proteoglycan subunit by equilibrium-density-gradient centrifugation in a CsCl-4M-guanidinium chloride gradient. Interaction with calf skin-soluble tropocollagen was studied by CM-cellulose chromatography. The link-protein system did not interact, but proteoglycan from the bottom of the gradient did interact. In addition, when proteoglycan subunit was allowed to interact with collagen, there was a preferential binding to the αsub2/sub and βsub12/sub components, and this effect was also observed with the proteoglycan material obtained from the collagenase digests of 3M-MgClsub2/sub-soluble cartilage collagen complexes. However, specificity for αsub2/sub and βsub12/sub chains was not exhibited by chondroitin sulphate glycosaminoglycan, and it is therefore concluded that preference for αsub2/sub and βsub12/sub chains is a function of the intact proteoglycan structure./p