The Production of Specific Antibodies to Native Collagens with the Chain Compositions, [α1(I)]3, [α1(II)]3, and [α1(I)]2α2

The antigenic properties of collagen are of great interest both from the structural and clinical point of view. It has recently been indicated (1) that the triple-chain collagen molecule is an excellent model for studies designed to elucidate the interrelationships between sequential and conformation-dependent protein determinants. These studies demonstrated that antigenic determinants on the native calf skin collagen molecule (chain composition, [α1(I)]2α2 were either absent or greatly diminished in triple-helical molecules prepared from single types of chains and exhibiting the chain composition, [α1(I)]3 or (α2)3. It was concluded that in addition to the helical conformation of the native collagen molecule, full expression of the antigenic activity requires an appropriate juxtaposition of amino acid side chains from both α1(I) and α2 chains. The data presented here extend these observations to the genetically-distinct collagen which occurs only in cartilaginous structures. The latter collagen is comprised of three identical chains, designated α1(II), and therefore possesses the chain composition, [α1(II)]3 (2). In a given species, the α1(II) chain exhibits several differences in amino acid composition, primary structure, and carbohydrate content when compared to α1(I) or α2 chains (2). The results indicate that although molecules of the chain composition [α1(I)]2α2 and [α1(II)]3 have common conformational characteristics, they elicit specific antibody responses.