Prebiotic Chemistry and the Origin
of Life.
The possible role of UV radiation
Claudia Crestini, Dipatimento di Scienze e Tecnologie Chimiche, Tor
Vergata University, Rome, Italy
Raffaele Saladino, Dipartimento di Agrobiologia ed Agrochimica,
Università della Tuscia, Viterbo, Italy.
WUTA08 1st Italian Workshop on
UltraViolet Techniques and Applications
The RNA World Hypothesis
Joyce, G.F. (2002) Nature 418, 214-221.
•Prebiotic chemistry: synthesis of biological molecules necessary for the birth of the
first living cell
•Origin of informational polymers
Claudia Crestini - WUTA08
Heterotrophic
theory
•A primordial soup of simple
molecules arose first
•driven by non biological
energy like radiation or heat
•assembled in complex
molecules and
•led to primitive life forms
Claudia Crestini - WUTA08
A heterotrophic origin of life?
Reducing atmosphere
Biomolecules synthesis
Prebiotic soup
Claudia Crestini - WUTA08
Complex molecules
Formamide as prebiotic probe
O
H
NH2
“Simulations based on Density Functional Theory show that
formamide is the most stable species with molecular formula “CHON”
Pauzat, F. et al. 6th EANA 2006
“This one-carbon molecule was detected in the gas phase of
interstellar medium” Crovisier, J. Astrobiology: Future Perspectives,
Kluwer Eds, 2004 Chapter 8, p. 179-203.
“in the long period comet Hale-Bopp“ Bockelee-Morvan,D. et al. Astr. Astrophys. 2000
“and tentatively in the solid phase on grains around the young stellar object W33A “
W.A. Schutte et al. Astr. Astrophys. 1999
Claudia Crestini - WUTA08
Formamide.
Phisical and Chemical properties
“Formamide has a high boiling point, without azeotropic effects, and a wide range of
uses as a solvent. It has an efficient solubilizing effect on nucleobases, nucleosides,
nucleotides, amino acids, proteins, sugars, metalsand salts”
Becker, B. J. Chem. Eng. 1970
Colloids and surfacesA: Physicochem Eng. Aspects 2003
219: 281-290.
A comparison of micelle formation of ionic
surfactants in formamide, in N-methylformamide
and in N, N-dimethylformamide.
M.Salim Akhter, Sadeq M. Alawi
Langmuir. 2004 Jan 20;20(2):329-35.
Solvation dynamics of formamide and
N, N-dimethylformamide in aerosol OT reverse micelles.
Shirota H, Segawa H.
Claudia Crestini - WUTA08
Elemental formamide chemistry
O
HNCO H2
Sugars
HCN H2O
NH3
H
CO
Formaldehyde
Thermal (C)
degradation
> 210 °C
(Lin, Langmuir 1994)
(D)
Thermal
degradation
radical
conditions
(Hofmann, Ber.
1882)
O
(A)
O
(B)
+ H2O
HCN + H2O
Hydrogen
cyanide
H
t1/2= ca. 40 yr
at 60°C and
pH 6.0
H2N
H
Formamide
Claudia Crestini - WUTA08
t1/2 ca. 10 yr
at 30°C and
pH 6.0
NH4+ O
H
Ammonium formate
The mineral
Honeycomb
Role of minerals metals
and metal oxides in
prebiotic chemistry
Claudia Crestini - WUTA08
The role of minerals and metal oxides on
prebiotic processes. A general overview
 Minerals can accumulate the prebiotic precursors
(concentration effect)
 Minerals can act as catalytic environments, reducing
the activation energy for the formation of products
 Minerals can tune the selectivity of prebiotic syntheses
 Minerals may act as a template
 Minerals are benign environments to preserve newly
formed biomolecules from degradation
Claudia Crestini - WUTA08
Bioorganic Med. Chem. 9 (2001) 1249-1253
A Possible Prebiotic Synthesis of Purine, Adenine, Cytosine, and 4(3H)Pyrimidinone From Formamide: Implications for the Origin of Life
Raffaele Saladino, Claudia Crestini, Giovanna Costanzo, Rodolfo Negri and Ernesto Di Mauro
Claudia Crestini - WUTA08
Analyzing the reaction mechanism. 13C/15NNMR Experiments “route of the purine ring”
Heat
* NH2COH
* NH2COH + H2O
HCN + H2O
HCO2NH4
Claudia Crestini - WUTA08
Analyzing the reaction mechanism. “route of the
pyrimidine ring”
Claudia Crestini - WUTA08
Toward an extraterrestrial synthesis of nucleobases
Draco constellation
Anselm Kiefer
High Museum of Art
Atlanta, USA
Cosmic dust
Claudia Crestini - WUTA08
Cosmic dust analogues preparation
1) Fe2SiO4* (Fayalite)
2) Mg0.5Fe1.5SiO4 *
3) MgFeSiO4 * (Olivine)
SiO2, MgO,
FeO2
Laser
Ablation
4) Mg1.5Fe0.5 SiO4 *
5)Mg2SiO4 * (Fosferite)
Cosmic dust analogue olivines (Mg,Fe)2SiO4 are
synthesized by laser ablation technique (Nd-YAG 108
Wcm-2). Oxide pellets of MgO, FeO2, SiO2 are used as
laser target vaporized in 10 mbar atmosphere of O2.
Brucato, J. R. et al in The Astronomy and Astrophysics Review, Volume 11,
Issue 2-3, pp. 97-152 (2003)
Claudia Crestini - WUTA08
ChemBioChem 6 (2005) 1368-1374
Synthesis and Degradation of Nucleic Acid Components by
Formamide and Cosmic Dust Analogues
Raffaele Saladino, Claudia Crestini, Veronica Neri, John R. Brucato, Luigi Colangeli, Fabiana
Ciciriello, Giovanna Costanzo, and Ernesto Di Mauro
Fe Si Mg
CDAs qualitative composition
olivine
fayalite
forsterite
NH 2
O
CDAs or olivine s
O
H
NH 2
N
NH
N
pyrimidinone
O
N
H
NH
O
cytosine
N
H
O
uracil
O
160°C, 48h
DHU:5,6-DiHydroUracil
NH
N
H
DHU
Claudia Crestini - WUTA08
O
O
N
N
N
N
H
purine
H2N
NH 2
urea
ChemBioChem 6 (2005) 1368-1374
Synthesis and Degradation of Nucleic Acid Components by
Formamide and Cosmic Dust Analogues
Raffaele Saladino, Claudia Crestini, Veronica Neri, John R. Brucato, Luigi Colangeli, Fabiana
Ciciriello, Giovanna Costanzo, and Ernesto Di Mauro
Yield defined as mg of product
per gram of formamide.
Fe Si Mg olivine
fayalite
forsterite
mg/g
NH 2
N
N
H
O
Claudia Crestini - WUTA08
Moving towards nucleosides
NH2
N
N
glycosidic
bond
N
N
O
O
R
O
ChemBioChem 4 (2003) 514-521
One-pot TiO2-Catalyzed Synthesis of Nucleic Bases and
Acyclonucleosides
From Formamide: Implications for the Origin of Life
Raffaele Saladino,a,* Claudia Crestini,b Umberto Ciambecchini,a Rodolfo Negri,c Giovanna
Costanzo,c Ernesto Di Mauro c,
Adenine, cytosine and thymine
3 acyclonucleosides
Claudia Crestini - WUTA08
Thymine synthetic pathway
* NH2COH
HCO2NH4
+ H2O
TiO2
O
O
H
HN
O
R. H. Barker, 1975
HCOH
* NH2COH
CH2OH
HN
O
N
H
H
O
O
H
HN
O
N
H
H
O
O
H3O
+ CH3
HN
O
N
H
N
H
H
O
- CO2
O
H
O
H
O
N
H
H
HN
O
N
+
H
O
CH3
H
Unic known one pot synthesis of thymine!
Claudia Crestini - WUTA08
CH2
HN
OH
O
+
H2
C
CH3
HN
O
N
H
Thymine from formamide
O
O
CH 3
HN
O
HCOH
HN
O
N
H
Formamide
N
H
Present day biosynthesis of thymidine
H
N
Methylentetrahydrofolate
N
H
N
H
O
CH 3
HN
HN
O
O
O
N
O
H2N
N
O
OP
H
N
OH
OP
N
N
OH
OH
H
N
N
H
HN
Tetrahydrofolate
N
H
Tetrahydrofolate
HN
H
N
H
N
+ HCOH
+ H2O
N
H
N
H
Claudia Crestini - WUTA08
NH
HN
O COO
N
H
_
_
COO
Nucleosides from formamide
N
N
N
N
O
OH
Compd 9
N
N
N
N
OH
OH
O
Compd 10
O
NH
H
N
N
N
N
O
OH
Claudia Crestini - WUTA08
Compd 11
Butlerow, 1861
HO-
O
H
.
H
Sugars
Single headed arrows represent aldol
Condensations. Double-headed arrows
represent enolizations. Aldotreose can
undergo a reverse aldol condensation
Claudia Crestini - WUTA08
A novel formose reaction
Unic known prebiotic syntesis of nucleosides!
Claudia Crestini - WUTA08
Exploring the role of UV-radiation in prebiotic chemistry
UV radiation in prebiotic chemistry.
Pioneering studies
Diamminomalononitril cyclization to a key imidazole intermediate
Claudia Crestini - WUTA08
UV radiation in prebiotic chemistry.
Pyrimidine From Cyanoacetaldehyde
hn
30-50% yield
Double bond isomerization for cytosine ring closure
M. P. Robertson, S. L. Miller Nature 1995, 972.
Claudia Crestini - WUTA08
UV radiation in prebiotic chemistry.
Glyoxal From formaldehyde
H. Mordehai BioSystems 1979, 11(4), 227-32
Claudia Crestini - WUTA08
Exploring the role of UV-radiation on
formamide prebiotic chemistry
Photocatalysis and the origin of life: Synthesis of nucleoside bases from
Formamide on TiO2(001) single surface.
Senanayake, S. D. and Idriss, H. (2006) PNAS. USA 103
Uncorrected peak areas of desorbing products
The surface structures of TiO2 (001) single crystal
Exploring the role of UV-radiation
on formamide prebiotic chemistry
our interest is to develop novel prebiotic
chemistry of nucleic acids based on
formamide under uv irradiation in the
presence of minerals or selected organic
compounds that can act as photocatalysts.
we hope that the syncrotron facility can be
used for this novel approach to esobiology
Claudia Crestini - WUTA08
Thank you for the kind
attention!