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Searching for the Origins of Life in Interstellar Space

Searching for the Origins of Life in Interstellar Space. Michael Jarvis & the Research Group of Professor D. K. Bohme. Centre for Research in Mass Spectrometry, York University. Thursday, April 26, 2007. NGC 4526. Composition of the stars:. 90% hydrogen 10% helium

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Searching for the Origins of Life in Interstellar Space

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  1. Searching for the Origins of Life in Interstellar Space Michael Jarvis & the Research Group of Professor D. K. Bohme Centre for Research in Mass Spectrometry, York University Thursday, April 26, 2007. NGC 4526

  2. Composition of the stars: • 90% hydrogen • 10% helium • trace amounts of heavy elements Composition of interstellar clouds: • gas and dust grains • mostly hydrogen and helium • trace amounts of small molecules (H2O, CH2O, CH4, NH3, CO2, and CH3OH), in gas-phase and on the surface and in the interior of dust grains What is the chemical composition of our galaxy? Our Sun Horsehead nebula

  3. LIFE is abundant! In our galaxy, Earth is a very special place. Complex organic molecules are abundant! Earth atmosphere: N2(78%), O2(21%), Ar (0.9%), CO2(0.04%) H2O, O3, CFCs... Proteins DNA,RNA

  4. Topic of this presentation. What are the fundamental requirements for life? • (1) water • (2) nucleic acids and amino acids (organic polymers) (DNA,RNA) (proteins) 4-member oligonucleotide “Bradykinin”: arg–pro–pro–gly–phe–ser–pro–phe–arg

  5. (1) Organic compounds were delivered to Earth by interplanetary dust, meteorites, comets and asteroids: “Panspermia” (2) Organic compounds were synthesized on Earth. The required energy is provided by lightning, UV, cosmic radiation, thermal energy or radioactive decay. “Homegrown synthesis”. Where were organic compounds such as amino acids first formed? On Earth? Elsewhere? There are two (competing) theories: “Many of the interstellar molecules discovered to date are the same kinds detected in laboratory experiments specifically designed to synthesize prebiotic molecules. This fact suggests a universal prebiotic chemistry.” - Jan M. Hollis, NASA Goddard Space Flight Centre

  6. Can we “see” molecules in the interstellar medium? The Very Large Array (VLA), consisting of 27 radio antennas on the Plains of San Agustin, New Mexico, is one of the world’s premier astronomical radio observatories. Each antenna is 25 meters in diameter. The planetary nebula K3-35. The colors show the 3.6 cm emission. The various colours represent different intensities of emission.

  7. A recent discovery: In 2004, glycolaldehyde was discovered in a cold region (8 K) of the gas-and-dust cloud Sagittarius B2, 26,000 light years away, near the centre of our own Milky Way Galaxy. The discovery was made using the National Science Foundation’s giant Robert C. Byrd Green Bank Telescope (GBT). 2-carbon sugar 3-carbon sugar 5-carbon sugar (ribose) + The synthesis of ribose molecules is important because these molecules form the backbone structure of both DNA and RNA, the carriers of all genetic information. Radioastronomy is used to identify molecules based on unique “fingerprint” emissions or absorptions. • Molecules rotate end-over-end. • When they change from a higher rotational energy level to a lower rotational level, they emit radio waves (photons) at precise frequencies.

  8. Have amino acids been detected in the interstellar medium? INTERSTELLAR GLYCINE Y.-J. Kuan, S.B. Charnley, et al. Astrophys. J. 593: 848-867 (2003) “…27 glycine lines were detected …in one or more sources..” A RIGOROUS ATTEMPT TO VERIFY INTERSTELLAR GLYCINE L.E. Snyder et al. Astrophys. J. 619: 914-930 (2005) “We conclude that key lines necessary for an interstellar glycine identification have not yet been found.”

  9. Nonetheless, biological material has been found in ppm quantities in meteorites that have impacted on Earth. • more than 70 different amino acids • carboxylic acids • pyrimidine • purine Thus, the presence of glycine in the interstellar medium has not yet been confirmed, but the possibility cannot be ruled out…

  10. Amino acid composition in two CI (Ivuna and Orgeuil) and two CM (Murchison* and Murray) meteorites: Amino acid CI(%) CM(%) Glycine 17 17 -amino acids 17 63 ,-amino acids 66 20 *More than 70 different amino acids were detected in the Murchison meteorite! The “carbonaceous chondrite” class of meteorites have been found to contain up to 60 ppm of amino acids! CI Chondrites: • cometary origin (material from interstellar medium) CM Chondrites: • asteroidal origin (material from solar system)

  11. Let’s see if we can generate amino acids from starting materials, involving ions, that are known to exist in the ISM. • gas and dust grains • mostly hydrogen and helium • trace amounts of small molecules (H2O, CH2O, CH4, NH3, CO2, and CH3OH), in gas-phase and on the surface and in the interior of dust grains CH+ (vis), CF+, CO+, NO+, SO+, H3+ (IR), HCO+, COH+, HCS+, N2H+, H3O+, HOCO+, HCNH+, H2COH+, HC3NH+, C6H-, C4H-, C8H- In our laboratory we study gas-phase ion chemistry. Why are ion/molecule reactions important in the ISM? • They are largely unaffected by extreme low temperatures (10-20K). • They are ~100 times faster than neutral/neutral reactions.

  12. Selected-ion flow tube/triple quadrupole mass spectrometer (SIFT/QqQ)

  13. “Simulating” the environment of the interstellar medium: • He as a buffer gas. • Pressure of only 0.35 Torr (0.0005 atm). • Reacting ions and molecules have no translational kinetic energy reagent molecules (variable flow) To Roots Blower Analysis and quantitation in quadrupole mass spectrometer Ions enter instrument Fixed reaction time

  14. Success!! • NH2OH+ + CH3COOH  NH2CH2COOH+(ionized glycine) • NH2OH2+ + CH3COOH  NH3CH2COOH+(protonated glycine) • OH+O bonding allows N-C bond formation (Blagojevic et al., Mon. Not. R. Astron. Soc. 339 (2003) L7-L11.) Several attempts to generate glycine were unsuccessful: CH3NH2+ + HCOOH CH3NH2+ + CO2 CH3NH2+ + CO + H2O NH3+ + CH3COOH CH2COOH+ + NH3 N-O bond formation is preferred over C-C and N-C bond formation.

  15. NH2OH+ + CH3COOH  NH2CH2COOH+ Some background on the precursors: Acetic acid:CH2+ + CO  CH2CO+ + hv CH2CO+ + 2H2O  CH3COOH+ + H2O Has been detected in ISM (1997) Hydroxylamine: NH3(s) + H2O(s) + hv  NH2OH(g) + other products Nishi et al. (J. Chem. Phys., 80, 3898, 1984) Undetected in ISM (so far) • NH2OH will be made in irradiation of interstellar ice (as shown by Nishi et al.). • Charnley et al. (Sept. 2001) proposed that NH2OH should be one of the major components of interstellar ice. It can be formed by radical hydrogenation of NO on the surface of dust grains.

  16. Comparing the fragmentation of our product ion with that of commercial (ie. purchased) glycine: • Increasing the voltage on the nose cone induces energetic collisions between ions and the neutral buffer gas. • The specific fragmentation patterns and appearance energies can be used as a “chemical fingerprint” to identify unknowns.

  17. Computational Chemistry results: (NH2OH)H+ + CH3COOH Potential energy landscape for the reaction between protonated hydroxyl amine and acetic acid to produce GlyH+ B3LYP/6-311++G(df,pd) (Galina Orlova)

  18. The isomer formed is b-alanine... … this can be confirmed from the observed fragmentation pattern. Biological isomer Non-biological isomer (protonated) a-alanine (protonated) b-alanine Larger amino acids: Synthesizing alanine Buoyed by our great success synthesizing glycine via a gas-phase ion/molecule reaction, we have attempted to synthesize alanine in a similar manner. NH2OH+ + CH3CH2COOH  NH2CH2CH2COOH+(ionized alanine) NH2OH2+ + CH3CH2COOH  NH3CH2CH2COOH+(protonated alanine)

  19. The “carbonaceous chondrite” class of meteorites have been found to contain up to 60 ppm of amino acids! CI Chondrites: • cometary origin (material from interstellar medium) CM Chondrites: • asteroidal origin (material from solar system) Amino acid composition in two CI (Ivuna and Orgeuil) and two CM (Murchison and Murray) meteorites: Amino acid CI(%) CM(%) Glycine 17 17 -amino acids 17 63 b-alanine 401 other ,-amino acids 26 19

  20. Computational Chemistry results: (NH2OH)H+ + CH3CH2COOH Potential energy landscape for the reaction between protonated hydroxyl amine and propanoic acid to produce β-AlaH+ (solid line) and α-AlaH+ (dotted line) B3LYP/6-311++(df,pd) (Galina Orlova)

  21. NH2CH2COOH NH2CH2CH2COOH M+ H M e- NH3CH2COOH+ NH3CH2CH2COOH+ NH2CH2COOH+ NH2CH2CH2COOH+ CH3COOH CH3CH2COOH CH3COOH CH3CH2COOH -H2O -H2O hv/A+ RH+ NH2OH+ NH2OH NH2OH2+ Interstellar gas hv, heat Interstellar ice hv hv NH3(s) + H2O(s) NH2OH NO + 3H M and A represent any neutral atom / molecule with a suitable IE. RH+ represents a proton carrier with PA(R) < PA(NH2OH). (Blagojevic et al., Mon. Not. R. Astron. Soc. 339 (2003) L7-L11.)

  22. From starting materials that are present in the ISM, we have demonstrated a mechanism for the interstellar synthesis of glycine and b-alanine!!! NH2,3OH+ + CH3COOH  NH2,3CH2COOH+ NH2,3OH+ + CH3CH2COOH  NH2,3CH2CH2COOH+ Some Conclusions • “Precursors to life” such as amino acids may have been delivered to Earth by meteorites, comets, etc. • Remote sensing of amino acids in the ISM with radiotelescopes has proved inconclusive. However, analysis of meteorites provides direct evidence of their presence. • The synthesis of specifically b-alanine supports the hypothesis that “CI chondrite” meteorites have interstellar origins.

  23. Acknowledgements • York University • Professor D.K. Bohme • Dr. Voislav Blagojevic • Bohme research group • Australian National University • Dr. Simon Petrie • St Francis Xavier University • Professor Galina Orlova

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