Ajikumar Parayil Kumaran, Lakshminarayanan Rajamani, Ong Boon Tee, Valiyaveettil Suresh, Kini R Manjunatha
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Biomacromolecules. 2003 Sep-Oct;4(5):1321-6. doi: 10.1021/bm034101b.
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.
鹅蛋壳钙结合蛋白是一种含有132个氨基酸残基的新型鹅蛋壳基质蛋白，在体外结晶实验中可诱导多晶方解石聚集体的形成。鹅蛋壳钙结合蛋白的中心区域以存在多个带电荷氨基酸为特征。为了研究带电荷氨基酸多重体在晶体成核中的具体作用，合成并表征了三种短肽REWD-16、REWDP-17（含有双电荷对）和RADA-16（交替带电荷残基）。使用圆二色性、内源色氨酸荧光和动态光散射实验研究了这些肽在溶液中的聚集情况。在体外结晶实验中，肽REWD-16和REWDP-17诱导了多晶方解石晶体聚集体的形成，而RADA-16在方解石晶体形态或聚集体形成方面未诱导出显著变化。使用X射线衍射和扫描电子显微镜对方解石晶体的晶格和形态进行了表征。本文讨论的结果揭示了带电荷氨基酸残基多重体对溶液中多晶方解石晶体聚集体成核的重要性。
