BIOCHEMICAL AND IMMUNOLOGICAL CHARACTERIZATION OF COLLAGEN MOLECULES FROM ECHINOTHURIOID SEA-URCHIN ASTHENOSOMA-IJIMAI

Collagens collected from the test (the external hard covering of invertebrates) of the sea urchin, Asthenosoma ijimai, were characterized biochemically and immunologically. The amino-acid composition was typical of that of mammalian collagens. Crystals of segment-long-spacing showed that the molecules of sea urchin collagen were 300 nm long. Selective salt precipitation revealed that the collagen has the same solubility characteristics as type I collagen. The collagen was denatured at 23.1°C. Anti-sea urchin collagen antisera were immunologically cross-reacted with collagens of the same species and the starfish Asterina pectinifera. However, the antisera showed no or slight responses to collagens of bovine type I, II, III, IV and V. The collagen molecules contained four α-chains, named α1(SU), α2(SU), α3(SU) and α4(SU), respectively. All of the four α-chains were eluted in the same fraction on gel filtration chromatography. Chains of α1(SU) and α2(SU) were extracted earlier than α3(SU) and α4(SU) during pepsin digestion. Other biochemical and immunological analyses clearly demonstrated that test of sea urchins contains two genetically different, but biochemically similar, species of collagens, one of which is composed of α1(SU) and α2(SU) chains, and the other of α3(SU) and α4(SU). © 1990.