Immunological relationships between proteoglycans of different hydrodynamic size from articular cartilage of foetal and mature pigs

Abstract

Proteoglycans were extracted from articular and laryngeal cartilages of foetal and mature pigs. Antisera were prepared to extracts containing protoglycans whose size had been determined by gel chromatography. The smallest, which were separated on 6% agarose, gave a single precipitin line without needing prior digestion with hyaluronidase. Proteoglycans large enough to be excluded from 6% agarose failed to react in double diffusion and were inacapable of absorbing specific antibody unless first digested with hyaluronides, implying a difference in structure between proteoglycans of different size. After digestion, however, the larger proteoglycans effectively absorbed specific antibody and produced multiple precipitation line, consistent with the presence of several core proteins. One of these lines which developed more rapidly than the rest appeared towards the antibody well and showed identify with the determinant of the smallest proteoglycans. This determinant however, was not dissociated from the intact proteoglycans by treatment with quanidine · HCl. When the largest proteoglycans were digested with hyaluronidase and diffused against antiserum to purified small proteoglycans two precipitin lines were produced. The one nearer the antibody well showed complete identity with the determinant of the small proteoglycans, while the other, nearer the antigen well, fused with the above, suggesting that this determinant may also be amongst those on the core proteins of larger proteglycans.