Type V collagen from the chick embryo: biochemical, physicochemical and ultrastructural characteristics

Two collagen alpha chains have been isolated from whole 17 day chick embryos which are similar to the B chain or alpha 1(V) and the A chain or alpha 2(V) recently described in mammalian and avian tissues. A non-collagenous acidic protein was co-purified with the Type V collagen which was resistant to pepsin digestion. The molecular weight, circular dichroism spectrum, melting temperature and diffusion coefficient of the native Type V collagen and isolated alpha chains were similar to values obtained for other chick collagen types. The SLS crystallite of Type V collagen had a distinct pattern of banding as identified by electron microscopy. We consistently observed more alpha 2(V) than alpha 1(V) following both CM-cellulose and QAE-Sephadex ion exchange chromatography of denatured Type V collagen, but unusual solubility properties and recoveries of the alpha 1(V) chain may have diminished its relative amount. In addition we have found that the alpha 1(V) chains are chemically heterogeneous and one component electrophoreses as an alpha 2(V) chain on SDS gels.