Purification and characterization of a matrix shell protein from the shell of scallop <Emphasis Type="Italic">Patinopecten yessoensis</Emphasis>

ABSTRACT:   A new protein named MSP-SC (matrix shell protein from scallop) with a molecular weight of 14 kDa was isolated from the shell of a scallop, Patinopecten yessoensis , using gel filtration column chromatography, ion exchange column chromatography, and reverse phase C4 column chromatography. A comparison of the known protein sequences with the N-terminal sequence of MSP-SC showed that the protein sequence of MSP-SC was novel. Immunohistochemistry using a polyclonal antibody against MSP-SC showed that MSP-SC is expressed in the mantle pallial cell layer but not in the muscle tissue, and showed a punctate distribution along the horizontal calcified layer in the shell. The isolated MSP-SC inhibited the formation of calcium carbonate (CaCO₃) crystals in a dose-dependent manner. The CaCO₃ crystals grown in the presence of a lower concentration of MSP-SC were much larger and aggregated when compared with those formed in the absence of MSP-SC. In addition, the crystal had a radial and not cubical morphology. These results suggest that MSP-SC regulates the formation and the morphology of CaCO₃ crystals in the shell. Moreover, its ability to aggregate CaCO₃ crystals and its localization along the horizontal calcified layer in the shell suggest that MSP-SC may serve to connect the CaCO₃ layers in the scallop shell.