Proline incorporation into the proline and hydroxyproline of earthworm-cuticle collagen.

Abstract

Abstract Studies in vivo of the incorporation of proline into earthworm cuticle have shown that, as with vertebrate collagens, proline and not free hydroxyproline is the source of both proline and hydroxyproline in cuticle collagen. Purified salt-soluble cuticle collagen preparations contain a component highly labeled in proline and resistant to collagenase (EC 3.4.4.19), but sensitive to trypsin (EC 3.4.4.4). The labeled proline in crude collagen preparations, although much higher in specific activity than hydroxyline, decays with about the same time-constant as the hydroxyproline; this and related observations suggest that injection-stimulated synthesis rather than normal turnover is being measured in these experiments. Digestion of cuticle collagen with collagenase releases most of the hydroxyproline in dialyzable form, implying extensive degradation to small fragments.