HR: 1330h
AN: B12C-0789    [PDF]
TI: An investigation of di-peptide modulation of calcite growth
AU: * Han, N
EM: nhan@vt.edu
AF: Virginia Tech, Department of Geosciences, Blacksburg, VA 24061 United States
AU: Grantham, M C
EM: grantham@eas.gatech.edu
AF: Georgia Tech, School of Earth and Atmospheric Sciences, Atlanta, GA 30332 United States
AU: De Yoreo, J J
EM: deyoreo1@llnl.gov
AF: Lawrence Livermore National Laboratory, Dept. Chemistry and Materials Sciences, Livermore, CA 94551 United States
AU: Dove, P M
EM: dove@vt.edu
AF: Virginia Tech, Department of Geosciences, Blacksburg, VA 24061 United States
AB: The central role(s) of the organic component in biologically controlled mineralization is widely recognized. These proteins are characterized by a high proportion of acidic amino acids, especially aspartate, Asp. Knowledge of the relationship between the structure of the organic components that give specialized functionality and their effect on crystallization is essential for understanding mineralization mechanisms. However, our current understanding of mechanisms by which these complex compounds promote, direct, and inhibit growth is very limited. As a step toward building a comprehensive model for protein controls on the directed growth of calcite, we are investigating the interactions of five di-peptides with the calcite surface during near-equilibrium growth. Using in situ Fluid Cell AFM, the effects of these Asp-Amino acid peptides on growth rate and hillock morphology were determined at near equilibrium conditions and 23.5C. Calcium and carbonate activity ratios are held to approximately 1.0 for all solutions, pH is 8.5, and ionic strength is 0.10 molal. Each of the peptides induces strong changes in growth morphology by changing the step edge morphology but each has a structure-specific effect on hillock morphology. Their impacts on the growth kinetics fall into two groups determined by functional group properties. Our findings for these simple compounds suggest predictable relations between the functional group chemistry of different peptides and indicate the cooperative nature of multiple groups in causing a suite of specialized effects on growth. This reiterates the site-specific nature of organic interactions with the kink-sites at calcite step edges.
DE: 0400 Biogeosciences
DE: 1045 Low-temperature geochemistry
DE: 1050 Marine geochemistry (4835, 4850)
DE: 4805 Biogeochemical cycles (1615)
DE: 4825 Geochemistry
SC: Biogeosciences [B]
MN: 2003 Fall Meeting