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

23