MONTMORILLONITE CLAY CATALYSIS By: Aimee Beaudette

RNA WORLD HYPOTHESIS  Self replicating RNA is the precursor to current life.  Stores genetic information and catalyzes chemical reactions.  Evolution resulted in today’s DNA/protein world.  DNA is more stable and proteins have a greater variety of monomers

RIBONUCLEOTIDES  Building blocks of RNA molecules  Ribonucleotides are important for both genetic and catalytic reasons

TRIPHOSPHATE RIBONUCLEOTIDE BASE

DIPHOSPHATE RIBONUCLEOTIDES BASE

MONOPHOSPHATE RIBONUCLEOTIDE  Monophosphate ribonucleotides are the repeating structure in an RNA polymer. BASE

IMIDAZOLE  When attached to the ribonucleotide the second nitrogen becomes protonated.  This makes Imidazole an incredible leaving group.

MONTMOROLLONITE CLAY STRUCTURE

WHERE?  Montmorillonite clay forms from volcanic activity.  Formed as soot settles out in water.  Also found on Mars.

WHY IS CLAY IMPORTANT?  Montmorillonite has been found to catalyze the reaction of 5 ’ activated nucleotides, forming RNA oligomers  Keeps nucleotides in the same plane, encouraging nucleophilic interactions  Acts as a general acid or base

PROBLEMS?  Monophosphate ribonucleotides form cyclic dimers in solution making them unreactive, montmorillonite clay mitigates this.  Hydrolysis can cause the imidazole group to leave before the reaction.  This leaves just a monophosphate ribonucleotide, that can attack with its 3’ hydroxyl but whose phosphate is not activated and won’t undergo nucleophilic substitution.

STUDYING CATALYTIC PROPERTIES  The clay is acidified to replace the large cations and any organics with protons, allowing more room for nucleotides.  The clay is then titrated to a pH of 7 using NaOH.  Mix clay 1M NaCl solution with activated nucleotides (ImpA)  Allow reactions to proceed for a day  Use HPLC to determine sizes of oligomers in solution

 Have found oligomers up to 50 nucleotides long  Ongoing research

REFERENCES 1. Albaran, G., Negron-Mendoza, A., & Ramos-Bernal, S. (1996). Clays as natural catalyst in prebiotic provesses. In J. Chela-Flores & F. Raulin (Eds.), Chemical Evolution: Physics of the Origins of Life (pp ). Boston: Kluwer Academic Publishers. 2. Aldersley, M. F., C. Josh P. C., Price, J. D., Ferris, J. P., The role of montmorillonite in its catalysis of RNA synthesis, Applied Clay Science, 54, Issue 1, November 2011, Pages 1-14, ISSN , /j.clay ( 3. Blitz, I. (2008). Braun Group People. Retrieved from: Ferris, J. P., (1998). Catalyzed RNA synthesis of the RNA world. In Brack, A. (Ed.), The Molecular Origins of Life. (pp ). Cambridge, UK: Cambridge University Press. 5. Gesteland, R.F., Cech, T. R., & Atkins, J. F. (Eds.). (1999). The RNA World (2 nd ed.). Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press. 6. Joshi, P. C., Aldersley, M. F., Delano, J. W., Ferris, J. P. (2009). Mechanism of montmorillonite catalysis in the formation of RNA oligomers. Journal of the American Chemical Society, 131, doi: /ja Schwartz, A. W. (1998). Origins of the RNA World. In Brack, A. (Ed.), The Molecular Origins of Life. (pp ). Cambridge, UK: Cambridge University Press.