title: Eggshell matrix protein mimics: designer peptides to induce the nucleation of calcite crystal aggregates in solution.
abstract: Ansocalcin is a novel goose eggshell matrix protein with 132 amino acid residues, which induces the formation of polycrystalline calcite aggregates in in vitro crystallization experiments. The central region of ansocalcin is characterized by the presence of multiplets of charged amino acids. To investigate the specific role of charged amino acid multiplets in the crystal nucleation, three short peptides REWD-16, REWDP-17 (containing charged doublets), and RADA-16 (alternating charged residues) were synthesized and characterized. The aggregation of these peptides in solution was investigated using circular dichroism, intrinsic tryptophan fluorescence, and dynamic light scattering experiments. The peptides REWD-16 and REWDP-17 induced the polycrystalline calcite crystal aggregates, whereas RADA-16 did not induce significant changes in calcite crystal morphology or aggregate formation in in vitro crystallization experiments. The lattice and morphology of the calcite crystals were characterized using X-ray diffraction and scanning electron microscope. The results discussed in this paper reveal the importance of multiplets of charged amino acid residues toward the nucleation of polycrystalline calcite crystal aggregates in solution.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Parayil Kumaran
authors.initials: PK
authors.lastname: Ajikumar
authors.forename: Rajamani
authors.initials: R
authors.lastname: Lakshminarayanan
authors.forename: Boon Tee
authors.initials: BT
authors.lastname: Ong
authors.forename: Suresh
authors.initials: S
authors.lastname: Valiyaveettil
authors.forename: R Manjunatha
authors.initials: RM
authors.lastname: Kini
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002119:Calcium Carbonate / Q000737:chemistry*; D003460:Crystallization; D004527:Egg Proteins / Q000737:chemistry*; D005777:Geese; D018716:Molecular Mimicry; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry; D012996:Solutions; D013057:Spectrum Analysis
chemical_list: D004527:Egg Proteins; D010455:Peptides; D012996:Solutions; D002119:Calcium Carbonate