HYDROTHERMAL PRODUCTION OF AMPHIPHILIC MOLECULES FROM PYRUVATE

1. HYDROTHERMAL PRODUCTION OF AMPHIPHILIC MOLECULESFROM PYRUVATE R. M. Hazen, G. D. Cody, D. W. Deamer, H. S. Yoder, Jr., J. Blank, A. Sharma, H. Morowitz ACS Session on Hydrothermal Chemistry San Diego, 5 April 2001

2. HAROLD MOROWITZ’S QUESTION • Will hydrothermal conditions promote the carboxylation of pyruvic acid?

3. Experimental Rationale • These experiments are not intended to mimic a prebiotic geochemical environment. • They are intended to explore reaction pathways of pyruvic acid under hydrothermal conditions. • Once such pathways are deduced, then additional experiments to optimize select pathways under plausible prebiotic conditions may be warranted.

4. Reactions of Pyruvic Acid Temperature = 150 to 300 C; Pressure = 0.05 to 0.5 GPa

5. Reactions of Pyruvic Acid – Methylsuccinic Acid Methylsuccinic acid forms by dimerization and subsequent decarboxylation of pyruvic acid.

6. Wilhelmy Plate Analysis Surface active molecules reduce the surface tension of water. This response is typical of vesicle-forming molecules

7. SELDI Laser desorption/ionization time-of-flight mass spectrometry reveals homologous series of polymerization reactions. I 100 200 300 Mass (Daltons)

8. Reactions of Pyruvic Acid – Substituted Aromatics A complex suite of substituted aromatic molecules forms by Aldol condensation and subsequent cycloaddition reactions.

9. Decarboxylation of Pyruvic Acid HDAC observations of CO2 formation.

10. Raman Spectrum of Pyruvic Acid(Room conditions in HDAC)

11. Raman Spectra of Pyruvic Acid(P & T in HDAC)

12. Stability of Pyruvic Acid at P and T In 2-hour experiments, pyruvic acid is rapidly consumed.

13. Reaction of Pyruvic Acid to Methylsuccinic Acid Maximum yields occur at 250 C and low pressure.

14. Reaction of Pyruvic Acid to “Product B” P and T both enhance yields of aromatic compounds.

15. Hydrothermal Organic Synthesis • Gold tube reactors in an internally-heated, gas-media, high-pressure apparatus

16. Hydrothermal Organic Synthesis - HDAC Hydrothermal Organic Synthesis • Hydrothermal Diamond • Anvil Cell

17. Pyruvic Acid • Reactants: Pyruvic acid + CO2 + H2O • Conditions: 200oC 2,000 atm 2 hours • Products: A diverse suite of organic molecules

18. Self-Assembly of Amphiphiles Amphiphilic molecules are observed to assemble into bilayers. 0.2 m Amphiphilic components extracted from the Murchison meteorite form membrane-like structures.

19. 2-D Liquid Chromatography Silica gel plate in visible light Silica gel plate in UV light

20. Comparison with Murchison Organics Pyruvic acid reactants Murchison meteorite

21. Comparison with Murchison Organics Pyruvic acid reactants Murchison meteorite Vesicle formation in phosphate buffer solution (pH = 8.5)

22. Comparison with Murchison Organics Pyruvic acid reactants– tof MS Murchison alkanes - GC Analyses of vesicle-forming fraction

23. Vesicles Amphiphiles from Pyruvic Acid Form Vesicles

24. Pyruvic Acid Plays an Important Metabolic Role The carboxylation of pyruvic acid is an entry point to the reductive TCA cycle.

25. Conclusions • We did not observe the reaction of pyruvic acid + CO2 to oxaloacetic acid under our range of P, T, and X in the pure system C-O-H. • Polymerization of pyruvic acid and its products occurs readily under hydrothermal conditions. Temperature and pressure have a significant effect on the product suites and yields. • Products of pyruvic acid reactions under hydrothermal conditions include a suite of vesicle-forming amphiphiles.

26. Conclusions • Similarities between our experimental products and Murchison meteorite organics suggest a similar robust polymerization chemistry. • One goal of prebiotic synthesis experiments should be to document the range of plausible environments for such organic synthesis. We can’t evaluate the role of high-pressure and hydrothermal environments without doing the experiments.