THE MACROMOLECULAR STRUCTURE OF TYPE-VI COLLAGEN - FORMATION AND STABILITY OF FILAMENTS

Type-VI collagen microfilaments were directly isolated from human amni on without using strong denaturing reagents. The microfilaments were c haracterized by electron microscopy, SDS/PAGE and immunoprecipitation. There was no evidence of other components bound to the isolated filam ents and no covalent bonds between adjacent tetramers. The association between tetramers was further analyzed by studying the affinity betwe en globular domains and the helix of type-VI collagen. Solid-phase-bin ding assays and conventional column chromatography showed that the glo bular domains have a high affinity for each other and for the helices of type-VI collagen, indicating that filaments may be assembled and st abilized in the absence of additional components. Hyaluronan did not s tabilize the filaments nor facilitate the assembly of tetramers into f ilaments. The interaction between domains was also studied after modif ying the sugar moieties of type-VI collagen globular domains and monom eric triple-helical domains, he oligosaccharides are involved in helix -helix interactions but not in interactions of the globular domains wi th each other or with the triple helix.