title: In vitro regulation of CaCO(3) crystal polymorphism by the highly acidic molluscan shell protein Aspein.
abstract: Biominerals, especially molluscan shells, generally contain unusually acidic proteins. These proteins are believed to function in crystal nucleation and inhibition. We previously identified an unusually acidic protein Aspein from the pearl oyster Pinctada fucata. Here we show that Aspein can control the CaCO(3) polymorph (calcite/aragonite) in vitro. While aragonite is preferentially formed in Mg(2+) -rich solutions imitating the extrapallial fluids of marine molluscs, Aspein exclusively induced calcite precipitation. Our results suggest that Aspein is involved in the specific calcite formation in the prismatic layer. Experiments using truncated Aspein demonstrated that the aspartic acid rich domain is crucial for the calcite precipitation.
authors.affiliation: Department of Earth Evolution Sciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan. take_r_baggio10@hotmail.com
authors.forename: Takeshi
authors.initials: T
authors.lastname: Takeuchi
authors.forename: Isao
authors.initials: I
authors.lastname: Sarashina
authors.forename: Minoru
authors.initials: M
authors.lastname: Iijima
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Endo
mesh_terms: D000818:Animals; D002119:Calcium Carbonate / Q000378:metabolism*; D003460:Crystallization; D004591:Electrophoresis, Polyacrylamide Gel; D008274:Magnesium / Q000494:pharmacology; D008855:Microscopy, Electron, Scanning; D049911:Pinctada / Q000187:drug effects / Q000378:metabolism*; D011506:Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012996:Solutions; D013059:Spectrum Analysis, Raman
chemical_list: D011506:Proteins; D011994:Recombinant Proteins; D012996:Solutions; D002119:Calcium Carbonate; D008274:Magnesium