Identification of Molecular Binding Sites for Calcium in the Organic Matrix of Molluscan Shell,
Abstract
We have found calcium-binding activity, on the order of 1 to 3 times 10 to the -9th power mols calcium per microgram of matrix protein, in soluble matrix extracted from the shells of a variety of marine mollusks. Modification or destruction of a number of chemical groups, previously postulated to be active calcium-binding sites, failed to destroy or diminish the uptake of calcium in soluble proteins above 10,000 daltons molecular weight. Previously it had been suggested that mineralization in mollusks was initiated by binding of one or more calcium ions to dicarboxylic acids (Weiner and Hood 1975) or to ester sulfate groups (Crenshaw 1972). These hypotheses are weakened by the evidence found in this study. We have developed a technique for simply and repeatable carrying out in vivo assays of bivalve extrapallial fluid under a variety of experimental conditions. Using this technique we showed that calcium in sea water is taken up by the clam Mercenaria mercenaria and bound to a low molecular weight proteinaceous compound in the extrapallial fluid. The calcium-binding protein is very rich in histidine, and its molecular weight is probably considerably lower than reported by Crenshaw (1972).
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1982
- Accession Number
- ADA113551
Entities
People
- Melbourne R. Carriker
Organizations
- University of Delaware