A Combinatoric Approach
to the Study of MineralMolecule Interactions
Frontiers in Mineral Science 2007
Session A15: Mineral-Molecule Interactions
June 28, 2007
Robert Hazen, Geophysical Laboratory
Research Collaborators
Carnegie Institution
Hugh Churchill
Jim Cleaves
George Cody
Gözen Ertem
Tim Filley
Rebecca Martin
Jake Maule
Andrew Steele
George Washington Univ.
Glenn Goodfriend
Henry Teng
University of Colorado
Gifford Miller
Steven DeVogel
University of Arizona
Robert T. Downs
George Mason University
Harold Morowitz
Johns Hopkins University
Dimitri Sverjensky
Carnegie-Mellon University
Aravind Asthagiri
David Sholl
Smithsonian Institution
Tim Gooding
Detlef Rost
Ed Vicenzi
Spanish Astrobiology Inst.
Antonio Salgado-Serrano
Research Collaborators
Carnegie Institution
Hugh Churchill
Jim Cleaves
George Cody
Gözen Ertem
Tim Filley
Rebecca Martin
Jake Maule
Andrew Steele
George Washington Univ.
Glenn Goodfriend
Henry Teng
University of Colorado
Gifford Miller
Steven DeVogel
University of Arizona
Robert T. Downs
George Mason University
Harold Morowitz
Johns Hopkins University
Dimitri Sverjensky
Carnegie-Mellon University
Aravind Asthagiri
David Sholl
Smithsonian Institution
Tim Gooding
Detlef Rost
Ed Vicenzi
Spanish Astrobiology Inst.
Antonio Salgado-Serrano
Two Questions
(Possibly Related)
1. How do crystals interact with
organic molecules?
2. What processes selected life’s
idiosyncratic molecules?
Origin of Biomolecules:
The Problem
A fundamental attribute of life is a high
degree of molecular selectivity and
organization, but prebiotic synthesis
processes are indiscriminate.
What prebiotic processes might have
contributed to such selection and
organization?
Biomolecular Selectivity:
Amino Acids
• Only 20 biological amino
acids compared to >90 in
Murchison meteorite
• Only -H amino acids (i.e.,
no -methyl amino acids)
• Homochirality – L >> R
Biological Homochirality
Many of life’s essential molecules are chiral.
1
1
C
4
2
3
(L)-enantiomer
C
4
2
3
(R)-enantiomer
How did life on Earth become homochiral?
Annual sales of chiral pharmaceuticals
approaches $200 billion.
Our Hypothesis: Minerals Work
Our Hypothesis: Minerals Work
Aspartic acid on calcite
Lysine on quartz
TCA on calcite
TCA on feldspar
Quartz – SiO2
Quartz is the only common chiral
rock-forming mineral
Right
Left
Reports of successful chiral selections as early as the 1930s.
Yet all previous authors used powdered quartz!
Quartz: Face-Specific Adsorption
(01-11)
(10-11)
Quartz Crystal Faces
Courtesy of S. Parker
Quartz – (100) Face
Quartz – (101) Face
MIRROR
Quartz – (011) Face
Feldspar (110)
Feldspar (110)
Diopside – (110) Face
Diopside – (110) Face
Calcite – CaCO3
Calcite – (214) Face
Modeling Mineral-Molecule Interactions
Begin by bringing a D-alanine molecule
close to an unrelaxed calcite (214) surface.
initial
final
H
N
C
O
Ca
D-Alanine-Calcite (214) Interactions
The stable converged configuration reveals
surface relaxation and Ca-O and O-H
interactions, but no strong third interaction.
initial
final
H
N
C
O
Ca
Alanine-Calcite (214) Interactions
D-alanine
L-alanine
Aspartic Acid-Calcite (214)
Interactions
(D)-ASP
(L)-ASP
The most stable configuration found for D- and Laspartic acid on calcite (214) surface. The D
enantiomer is favored by 8 Kcal/mol.
A General Research Strategy
How do we evaluate interactions among
the numerous possible mineral-molecule
pairs?
We need a combinatoric approach.
Jake Maule, Andrew Steele and Rebecca Martin
A Combinatoric Strategy
ChipWriter
• Up to 126 minerals
• Up to 49,152 spots per
mineral
• Up to 96 different wells
• 100-micron spots
Microarrays of Cy3-labeled asparagine, glutamine
B dilutions.
A
and tyrosine
on glass at 20 serial
Each microarray was scanned simultaneously with 532nm/635nm lasers and
the fluorescence emission was captured at the wavelength bands of 557-592nm
(Cy3) and 650-690nm (Cy5). Each image shows the intensity of Cy3/Cy5
fluorescent bands at a focal distance of 60mm (left) and 120mm (right).
C
Selective Adsorption on Minerals
ChipReader
• Simultaneous analyses
of 105 spots.
• D/L amino acid resolution
• Excitation wavelengths at
532 and 635 nm
A
B
Microarrays of Cy3-labeled L-lysine on left- and right-handed
quartz (100) faces at 8 serial dilutions. 150-micron spots.
Tagged Lysine on Quartz
Advances:
We can print microarrays and observe
differential adsorption on mineral surfaces.
Problems:
Fluorescent tags significantly modify the
adsorption behavior.
Most molecules of prebiotic interest are
not fluorescent.
Edward Vicenzi and Detlef Rost
ToF-SIMS Lab, Smithsonian Institution
Feldspar (010) in ToF-SIMS Sample Holder
ToF-SIMS
High-resolution ion
fragment maps of
150-micron L-lysine
spots on calcite (214).
X
X
L-Lysine
on Calcite (214)
300 AMU
107
106
Intensity
105
104
103
10
5
L lysine
calcite
102
101
C3H7+
100
20
40
60
80
100
120
140
160
180
200
220
240
260
280
mass / u
104
C2H5N+
C2H3O+
103
43Ca+ 42CaH+
102
m/Dm ~ 8000 FWHM
101
100
42.85
42.90
42.95
43.00
43.05
43.10
43.15
mass / u
9 x 13 Array on 1 x 1 x 0.3 cm feldspar plate.
AMINO ACIDS AND SUGARS ON FELDSPAR
(010) Face – 1 x 1 cm plate
D-Lysine on Feldspar (010)
DL-Xylose on Feldspar (010)
Mass vs. Intensity
for ~43 mass unit fragments
10
10
4
3
Intensity
10
C2H3O (43.02)
5
10
2
10
1
10
0
Key to Adsorbants
----- arabinose
----- lyxose
Pentose
Sugars
----- ribose
----- xylose
Amino Acid ----- lysine
42.85
42.90
42.95
C2H5N (43.04)
43.00
43.05
43.10
43.15
43.20
mass / u
CONCLUSIONS
• Many mineral surfaces have the potential
for chiral selection of plausible prebiotic
molecules.
• Microarray technology coupled with ToFSIMS provides a powerful experimental
means for combinatoric studies of mineralmolecule interactions.
With thanks to:
NASA Astrobiology Institute
National Science Foundation
Carnegie Institution of Washington