alexis morris mentor: dr. eric pattersondiscus/muccc/muccc20/muccc20 … · microsoft powerpoint -...
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Alexis Morris
Mentor: Dr. Eric Patterson
Astrobiology?Astrobiology?
Study of the origins of life What is life? Where is life?
Search for the precursors of precursors of biomolecules
‐Insight & Intelligence. Jun 7, 2011 “Biotechnology Instruments Being Used to Detect Alien Life”
Chemical Building Blocks of LifeChemical Building Blocks of Life
DNA/RNA
Carbohydrates
Lipids
Proteins
ProteinsProteins
Basic functional unit of the cell CatalysisCatalysis Structure Signaling
D f Defense Transport
Secondary Structure Primary Structure
A T Y NRG A T Y NRG
Protein building blocks: amino acidsProtein building blocks: amino acids
Amino acids have been detected
Murchison meteorite
Amino acids have been detected
Murchison meteorite Comets
Amino Acid MurchisonMeteorite
Glycine ●●●●
Alanine ●●●●
Proline ●
Valine ●●
Sarcosine ●●●
The Interstellar Medium (ISM)The Interstellar Medium (ISM)
I t t ll M di Interstellar Medium‐area between stars
Varies in temperature and density Molecular clouds Hot cores
Composed of mostly H2 and He 2
< 1% other elements
SpectroscopySpectroscopy
Search for LifeSearch for Life
Spectroscopy Organic matter is plentiful in space
Interstellar medium
H and C compounds
H, C, and O compounds
H, C, and N compounds
Other
compounds
CH3 C3O C3N C3SC4H C2H4O CH3NH2 MgCN4 2 4 3 2 g
H2CCC (CH3)2CO HC5N NaCN
C8H CH2OHCHO HC11N SiC4
Protein building blocks: amino acidsProtein building blocks: amino acids
Discovery of aminoacetonitrileDiscovery of aminoacetonitrile
CarbonH d
Atom Key
HydrogenNitrogenOxygen
Cyano vs CarboxyCyano vs Carboxy
• Barrier of 1.43 kcal/molC t bl i ISM
CarbonHydrogenNitrogen
Atom Key
• Cyano group more stable in ISM• 10‐15x less decomposition for –CN
Zhu et al. 2004
gOxygen
Bernstein et al. 2004
What we aim to do…
Propose different mechanisms of possible formation of amino acid precursors in the interstellar medium
f h f f h f See if the formation of the cyano precursors of Glycine, Alanine, Leucine, Isoleucine, Valine, …etc. are plausible in the ISMplausible in the ISM
Methods Optimizations were done using M06‐2X/6‐Optimizations were done using M06 2X/631G**(d,p). Computationally cheap Relatively accurate
G i d f l l i d Gaussian 09 was used to perform calculations and GaussView for structural analysis.
Excited states energies were obtained with TD‐DFT
Possible PrecursorsPossible Precursors(Cation/Anion products)
+ +
Acetonitrile Ethyl Formate Cation Anion
ΔHrxn= 200.1 kcal/molCarbonH d
Atom Key
HydrogenNitrogenOxygen
Possible PrecursorsPossible Precursors(Radical products)
+ +
Acetonitrile Ethyl Formate Radical Radical
ΔHrxn= 93.2 kcal/mol CarbonH d
Atom Key
HydrogenNitrogenOxygen
Formation of aminoacetonitrileFormation of aminoacetonitrileradical
++
ΔH = ‐73 6 kcal/molΔHrxn= 73.6 kcal/mol
Barrierless!!!
Basiuk 2004
Alanine‐CN
+
ΔHrxn= ‐74.7 kcal/mol CarbonHydrogen
Atom Key
rxn 74 7 / HydrogenNitrogenOxygen
Valine‐CN
+
ΔHrxn= ‐73.0 kcal/mol CarbonHydrogen
Atom Key
rxn 73 HydrogenNitrogenOxygen
Isoleucine‐CN
+
ΔHrxn= ‐72.6 kcal/mol CarbonHydrogen
Atom Key
HydrogenNitrogenOxygen
Leucine‐CN
+
ΔHrxn= ‐74.8 kcal/mol CarbonHydrogen
Atom Key
rxn 74 / HydrogenNitrogenOxygen
Summary
Aminoacetonitrile is a proposed precursor to amino
Summary
acids We have proposed several mechanisms of precursor f iformation Ethyl formate + acetonitrile
Radical Radical Cation/anionic
Proposed mechanism of alanine, leucine, isoleucine, valine precursor formation
D E iD E iThank you!
Dr. Eric Dr. Eric PattersonPatterson
F ll L b bFellow Lab members
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