Structures of the D-galactose oligosaccharides from earthworm cuticle collagen.

Earthworms have a thin layer of cuticle which covers the whole body and serves as a general protective function. This cuticle has the characteristic wide angle x-ray diffraction pattern of collagen (1, 2) and has an amino acid composition characteristic of collagen (3). Much of the dry weight of this cuticle can be extracted by neutral salt or weak acid and purified as a collagen (4, 5). Earthworm cuticle collagen has the amino acid . . composition (3, 5), the collagen -+ gelatin thermal transition (4, 5), and the susceptibility to collagenase (5) found with vertebrate collagens. It has, however, certain unusual properties such as a molecular weight of 1,900,OOO (4), a lack of periodic cross-striations under the electron microscope (5-7), a high content of hydroxyamino acids (3-5), and a high percentage of bound carbohydrate (3, 4, 8). A preliminary communication from this laboratory reported t.hat EC-collagen1 contained 12% n-galactose (8). About 70% of this n-galactose could be recovered as reduced disaccharide and reduced trisaccharide after treating the whole collagen with alkaline sodium borohydride, suggesting that these oligosaccharides are linked to the protein by alkali-sensitive linkages. Optical rotatory dispersion and proton magnetic resonance spectra