6533b828fe1ef96bd1289562

RESEARCH PRODUCT

Caspartin: thermal stability and occurrence in mollusk calcified tissues.

subject

description

8 pages; International audience; The fan mussel Pinna nobilis secretes a two-layered shell, the external layer of which is composed of long calcitic prisms. The dissolution of these prisms releases an assemblage of acidic intracrystalline proteins, among which caspartin, an Asp-rich protein (Marin et al., 2005). A polyclonal antibody raised against purified caspartin was used for estimating its thermal stability, and for investigating the presence of cross-reacting proteins in the shell matrices of several mollusks. In the first case, prisms of Pinna nobilis were heated at 100°C, for one to eleven days. The degradation of caspartin was followed on SDS-PAGE and on Western-blot. The experiment shows that caspartin is rather stable, and suggests that this protein might be preserved in recent fossil specimen. In the second case, shell matrices were extracted from numerous mollusks including bivalves, gastropods and cephalopods. They were subsequently tested on ELISA and on dot-blot, to check the presence of caspartin or imunologically related proteins. The pattern obtained is not superimposed with the mollusk phylogeny nor it is strictly correlated with the pattern of shell microstructures. The implications of our findings are briefly discussed.