Chiral Selection

2. Chiral Selection
 

This effort is a subset of the more general work on mineral-molecule interactions. The origin of life’s biochemical homochirality (i.e., the handedness of such common molecules as sugars and amino acids) is an ongoing problem in studies of life’s origins. Our hypothesis is that chiral mineral surfaces may have played a significant role in local selection and concentration of chiral molecules.

 

Hazen, R.M., T.R.Filley and G.A.Goodfriend (2001) Selective adsorption of L- and D-amino acids on calcite: implications for biochemical homochirality. Proceedings of the National Academy of Sciences (US), 98: 5487-5490.

 

Hazen, R.M. (2001) Life’s rocky start.  Scientific American, 284, #4, 76-85.

 

Hazen, R.M. and D. S. Sholl (2003) Chiral selection on inorganic crystalline surfaces. Nature Materials 2, 367-374.

 

Hazen, R. M. and D. S. Sholl (2003) Origins of biomolecular homochirality: selective molecular adsorption on crystalline surfaces.  Astrobiology 2, 598-599.

 

Hazen, R.M. (2004) Chiral crystal faces of common rock-forming minerals. In G. Palyi, C. Zucchi and L Cagglioti, Eds. Progress in Biological Chirality. New York: Elsevier, Chapter 11, pp.137-151.

 

Hazen, R. M. (2006) Mineral surfaces and the prebiotic selection and organization of biomolecules (Presidential Address to the Mineralogical Society of America). American Mineralogist 91, 1715-1729.

 

Asthagiri, A. and R. M. Hazen (2007) An ab initio study of adsorption of alanine on the chiral calcite (2131) surface. Molecular Simulation 33, 343-351.

 

Castro-Puyana, M., A. Salgado, R. M. Hazen, A. L. Crego and M. L. Marina (2008) Investiation of the enantioselective adsorption of 3-carboxy adipic acid on minerals by capillary electrophoresis. Electrophoresis, in press.

 

We are testing the hypothesis that handed molecules adsorb selectively onto handed crystal faces, such as the (214) surfaces of calcite. (Figure from Scientific American, Hazen, 2003).


FMOC (i.e., fluorescent-tagged) L-lysine binds preferentially to (100) faces of right-handed quartz, compared to left-handed quartz. Images on left show 1 x 3 mm areas of quartz crystals post wash, with 150-μm spots. Both quartz crystal faces were scanned at focal distance of maximum fluorescence signal, 550PMT, 10% power, 5-pixel resolution (Hazen et al 2004).


(A) ToF-SIMS macro-raster mode images of a 3 x 3 mm amino acid microarray on glass showing the mass 18.04 NH4+ ion fragment that is characteristic of all amino acids; dark lines correspond to ink marks and other surface contamination. (B) A single 150 μm array spot of lysine on calcite imaged using ToF-SIMS in the micro-raster mode for the mass 84.09 amino acid fragment (presumed to be C5H10N).


The most stable configurations found for D- and L-alanine on the calcite (214) surface (A and B, respectively). We find a negligible difference in adsorption energy.


The most stable configurations for D- and L-aspartate on the calcite (214) surface (A and B, respectively). The D enantiomer is favored by 8 Kcal/mol – the largest known enantiospecific effect.

  • For further information, see our project website