towards a molecular movie: transient 2d-ir spectroscopy peter hamm physikalisch chemisches institut,...

Towards a molecular movie: Transient 2D-IR spectroscopy

Peter Hamm

Physikalisch Chemisches Institut, Universität Zürich

B.L. de Groot and H. Grubmüller, Science 294, 2353-2357 (2001)http://www.mpibpc.gwdg.de/abteilungen/071/bgroot/gallery.html

Biosystems are Dynamical

Aquaporin-1

Structure Sensitive Methods

Scattering Methods(x-ray, electrons, neutrons) 2D-NMR

+ highest structure resolution power- works best in crystals

+ works best in solution+ high structure resolution power

+ intrinsic time resolution unlimited

- intrinsic time resolution very poor (1-100 ms)

Time Resolved Scattering Methods

2D-IR

+ intrinsic time resolution fast (1 ps) - structure resolution power low but non-zero

Site Basis Exciton Basis

01

10

00

Coupled Vibrational States

O

O

N

NC

C

2

1

H

Linear Coupling:

Frequency

CNH

C

O

CNH

C

O

CNH

C

O

HH

H

CNH

C

OR1 C

NH

C

OR3

CN

H

C

OR2

Frequency

Weak coupling,heterogeneous

Strong coupling,homogeneous

R2

R3

R1

Linear Spectroscopy

tp=100 fs=200 cm-1

E=1 µJ Spectrometer +232 Element MCT

Detector ArrayFabry Perot

Filter

Delay

Sample

2D-IR Spectroscopy: Setup

2D-IR Spectroscopy

O

O

N

NC

C

|0

|1

|2

|0‘

|1‘

|2‘

2D-IR Spectroscopy

O

O

N

NC

C

|10

|20|11‘

|00‘

|01‘

|02‘

2D-IR Spectroscopy: Equilibrium

Woutersen et al. J. Phys. Chem. B, 104, 11316-11320 (2000)Woutersen et al., PNAS 98, 11254-11258 (2001)Woutersen et al. J. Chem. Phys. 117, 6833-6840 (2002)

1600

1620

1640

1660

1680

1700

Pum

p F

requ

ency

[cm

-1]

1600 1620 1640 1660 1680 17001600 1620 1640 1660 1680 1700

Probe Frequency (cm-1)Probe Frequency [cm-1]

Conformation and distribution of conformations

Ultrafast equilibrium fluctuations

Our Dream: Molecular Movie

Photocleavable Peptide

C. Kolano, K. Gomann, W. Sander, Eur. J. Org. Chem. 2004, 20, 4167-4176.

h

?

1620 1640 1660 1680 1700 1720 1740 17600.0

0.1

0.2

Wavenumber [cm -1]

Ab

sorb

an

ce [

mO

D]

Photocleavable Peptide: IR spectrum

Boc-Cys-Pro-Aib-Cys-OMe

1625 1650 1675 1700 1725

1625

1650

1675

1700

pu

[cm

-1]

pr

[cm -1]

Equilibrium 2D Spectrum

1 ps

t2D-IR

IR Probe

Spectrometer +232 Element MCT

Detector Array

Delay

SampleFlow-Cell

Transient 2D Spectroscopy: Setup

UV Switch

Delay

Fabry PerotFilterIR Pump

Transient 2D-IR Spectra

3-100 ps 1 ps

tIRpump IRprobe

UVpump

3 ps 25 ps 100 ps

• MD Package: Gromacs; Gromos Force Field 43a1

• Starting geometry: Based on low-resolution x-ray structure

• Solvent box: Acetonitrile (1048 molecules)

Nonequilibrium MD Simulations

Equilibrium Simulation (NVT): 120 ns1 ns

Bondbreaking:Remove S-S Bond

No

n-E

quili

briu

m S

imu

latio

n

(NV

E):

60

0 p

s

0 100 200 300 400 500 600246

246

246

Time [ps]

OH

Dis

tanc

e [Å

]

MD Simulations: Example Trajectories

3.0 Å

0 100 200 300 400 500 600

2

3

4

5

6

OH

Dis

tan

ce [Å

]

Time [ps]

MD Simulations: Average

3.0 Å

6.1 Å

+

-

1625 1650 1675 1700 1725

1625

1650

1675

1700

pu

[cm

-1]

pr

[cm -1]


Equilibrium 2D Transient 2D

100

ps

C. Kolano, Nature 2006 in press

1625 1650 1675 1700 1725

1625

1650

1675

1700

pu

[cm

-1]

pr

[cm -1]


Equilibrium 2D Transient 2D

100

ps

And Finally: The Movie

Conclusion

Transient 2D-IR spectroscopy combines picosecond time resolution with microscopic structural information

Transient 2D-IR reveals new insight into fast structural dynamics of peptides, that

cannot be obtained otherwise.

An ultrafast molecular movie of the 3D-structure conceivable (in connection with isotope labeling)

Outlook: Isotope Labelling

h

13C=O13C=O

13C=18O13C=18O

-Helix Folding

University Zürich University Munich- Dr. Christoph Kolano - Prof. Wolfgang Zinth- Dr. Jens Bredenbeck - Dr. Jan Helbing University Bochum- Mariusz Kozinski - Dr. Christoph Kolano - Valentina Cervetto - Prof. Wolfram Sander- Harald Bregy- Ellen Backus Max Planck Institut, Martinsried - Virgiliu Botan - Dr. Christian Renner

- Prof. Luis MoroderMax Born Institut, Berlin- Dr. Sander Woutersen University of Toronto- Prof. Thomas Elsaesser - Prof. Andrew Woolley

University Frankfurt Financial Support- Prof. Josef Wachtveitl - Universität Zürich- Prof. Gerhards Stock - Swiss Science Foundation

- Deutsche Forschungsgemeinschaft

Acknowledgement

towards a molecular movie: transient 2d-ir spectroscopy peter hamm physikalisch chemisches institut,...

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