Paper Citing NAMD - Abstract
Cho, Kang Rae; Salter, E. Alan; De Yoreo, James J.; Wierzbicki, Andrzej; Elhadj, Selim; Huang, Yu; Qiu, S. Roger
Impact of Chiral Molecules on the Formation of Biominerals: A Calcium Oxalate Monohydrate Example
CRYSTAL GROWTH & DESIGN, 12:5939-5947, DEC 2012
Minerals in organisms often exhibit chiral shapes. The physical mechanism by which chiral information is transferred from molecules to crystal morphology is still not well-defined. In this article, we investigate the influence of chiral molecules on the growth of calcium oxalate monohydrate (COM), a mineral phase commonly found in solanacea plants and human kidney stones, by combining in situ atomic force microscopy (AFM) and molecular mechanics modeling. Three synthetic 6-residue linear aspartic acid-rich peptides of L-Asp(6), D-Asp(6), and L-Asp(3)-D-Asp(3) are used as surrogate molecules, with the first two being an enantiomeric pair. Our observations show that, while both L-Asp(6) and D-Asp(6) modify the growth of COM by interacting with specific steps on existing faces, the effect from the peptide L-Asp(3)-D-Asp(3) on COM growth is minimal. Furthermore, AFM images reveal that the two enantiomers have different binding preferences to steps that are related by mirror symmetry. As a result, growth morphologies with different chiralities emerge. Molecular modeling reveals the structural relationships between the atomic steps and the enantiomers that are responsible for the enantiomer-specific interactions and provides a prediction of relative binding strengths that are consistent with the experimental observations. Our studies support the general principle that the manifestation of gross chiral features in COM crystals grown in the presence of a foreign chiral agent is caused by differential stereochemical matching between the agent and the mirror symmetry-related features present on the growing surfaces.
