Adding dimensions to femtosecond spectroscopy: id, 2D and 3D infrared and visiblespectroscopies Martin T. Zanni

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1 Adding dimensions to femtosecond spectroscopy: id, 2D and 3D infrared and visiblespectroscopies Martin T. Zanni Department ofchemistry, University of Wisconsin-Madison, USA TuesdaY,3 May- 4:00 p.m, The invention of 2DIR spectroscopy about10 years ago has spawned a new fieldin theultrafast physics andchemistry communities. Byusing pulse sequences to manipulate thevibrational and/or electronic coherences of molecules, one can now collectspectra with2d lineshapes thatmeasure structural heterogeneity, and2dcorrelation spectra that resolve thecoupling andenergy transfer between eigenstates. These techniques are now being appliedto a wide range ofsystems, from biophysics to the energy sciences. Moreover, new technological advances in pulseshaping andtheirapplication to 2D spectroscopies now enable new applications andimproved pulse sequences. Inthistalk,Iwillhighlight how one uses pulse shaping to collect 2DIR andvis spectroscopies anddemonstrate itsapplication to amyloid fibre formation andcharge injection at organic-semiconductor interfaces.then, Iwill present recent work ondeveloping 3Dspectroscopies, which promise to further improve the range andimpact of multidimensional spectroscopy onmolecular dynamics.

2 Adding dimensions to femtosecond spectroscopy: 1D, 2D and 3D infrared and visible spectroscopies Martin Zanni, University of Wisconsin - Madison

3 Specialty: Multidimensional IR spectroscopy IR Technology Development Mid-IR pulse shaping Automated 2D IR spectroscopy New pulse sequences, 3D IR Heterodyned SFG spectroscopy Applications Membrane protein structure and dynamics CD3z, Influenza M2 H+, SARS, Ovispirin, KcsA Aggregation of amyloid fibers Type 2 diabetes and cataracts Electron transfer at semiconductor interfaces New Directions Super-resolution microscopy

4 2D IR Spectroscopy Linear IR Spectroscopy t 1 t 2 t 3

5 Amyloid fiber formation Human islet amyloid polypeptide (hiapp) involved in Type 2 diabetes Tycko Partially formed oligomers are more toxic than fully formed fibrils!!

6 Cytotoxicity Fibers Oligomers U Monomers I Toxic Intermediate F Fiber Ishii, Nature Struct. Mol. Biol., 2007

7 Methods for studying kinetics and structures U Monomer I Toxic Intermediate F Fiber Tht binding to beta-sheets Circular dichroism Flourescence Intensity

8 Structure Information Flourescence and CD will not solve the problem. Structural resolution is too low. Difficult to apply more standard structural tools (x-ray, NMR, ssnmr, EPR) Fibers are large and insoluble (and takes place in bilayer) Relatively fast kinetic process (minutes) Very few techniques that provide site-specific structural information on an evolving system, whether or not drugs are present. Two-dimensional IR Spectroscopy!! Residue-level structural information. Applies to all relevant timescales. Complex environments or aggregates.

9 Spectroscopy/structure: amide I mode of peptides random coil beta-sheet Local Modes Normal Modes 1645 cm cm cm -1 Frequency (cm -1 ) Frequency (cm -1 )

10 2D IR spectrum of hiapp fibers 13 C= 18 O hiapp: KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY

11 Objective fluorescence 2D IR spectroscopy Initiate Aggregation time Difficulties: Takes 15 min to 2 hours of averaging to collect a single 2D IR spectrum with standard methods. Aggregation not perfectly reproducible. Need to collect properly phased, absorptive 2D IR spectra on-the-fly. Solution: Rapid-scan, pulse shaping 2D IR spectroscopy (PNAS, 2007; PCCP 2009)

12 Experimental setup ZnSe wedges on translation stages (1 ps = 0.5 cm) Balanced heterodyne detection

13 Experimental setup ZnSe wedges on translation stages (1 ps = 0.5 cm) Balanced heterodyne detection Goal: Make 2D IR as easy to use as NMR Need: programmable pulse trains

14 Femtosecond pulse shaping lens Ge AOM lens grating grating AWG 2 18 microns

15 Direct mid-infrared pulse shaping Spectrum of shaped mid-infrared Intensity wavelength (nm) Amplitude 3 ns 665 ns time (μs) 500 pixels with programmable intensity and phase

16 Autocorrelation of a double pulse t 1 1 ps intensity (a. u.) 3 ps 2 ps time (ps)

17 Pump-probe experiments using a pulse shaper pump probe T Pulsed 2D IR (colinear) ω probe (cm -1 ) Just need to do a pump-probe experiment to get 2D IR data!!

18 Phase cycling to remove scatter φ 1 φ 2 φ 3 φ 4 No phase cycling Period = 7 Period = 9 Use a four-cycle pulse sequence to remove background and scatter S(0,0) S(π,0) + S(π,π) S(0, π) Takes 0.4 s (100 delay times)

19 Pulse shaping 2D IR W(CO) 6 in hexane (no cross peaks) Pump Probe ω probe (cm -1 ) Advantages and new capabilities: absorptive features that are perfectly phased perfect phase stability (can average indefinitely) rotating frame phase cycling (select Feynman paths, remove scatter) change pulse sequences by just programming (no optics) can separate the rephasing from non-rephasing spectra (Ogilvie, 2008) Extremely fast (no moving parts): 2D IR spectrum in 0.1 s (1 khz) PNAS, 2007; Review Article PCCP 2009 Now being built by about half the groups in the 2D IR community.

20 Protein Folding: hiapp amyloid fibers β-sheet Follow kinetics of secondary structure formation without deconvolution. Random Coil Strasfeld, Lin, Shim & MTZ JACS, 2008

21 Isotope labeling: 13 C= 18 O Ala25 hiapp: KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY 1645 cm cm cm cm cm -1 Frequency (cm -1 ) Frequency (cm -1 ) Can utilize the linewidths and cross peaks of a single residue.

22 Amylin aggregation Ala25 hiapp: KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY ω pump probe freq (cm-1) ω probe Cross peak indicates that Ala25 has beta-sheet secondary structure.

23 Isotope labeling: 13C=18O In-registry = coupling (β) /- 2β 1618 cm cm -1 Frequency of labels give information on growth and registry of strands. Thus, monitor formation of secondary structure. Frequency (cm -1 )

24 Kinetics of Isotope labels Ala25 hiapp: KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY Ala25 Ala25 Ala25 into a betasheet at the same time as the unlabeled residues e.g. it is average Val32 Labels exhibit different kinetic timescales!!!

25 Kinetics of Isotope labels Ala25 Ala25 Val32 Labels exhibit different kinetic timescales!?!?

26 Isotope labeling: 13C=18O Folding starts near the turn and propagates down the sheets. If the convention view was correct, then t 50 =1 for all residues.

27 Mechanism of hiapp fiber formation Random Coil Partly folded intermediate β-sheet at Val17 Hairpin forms to Ala25 N-terminus forms Fiber formation Possibly one of the most detailed structural mechanisms for amyloid aggregation. (PNAS, 2009)

28 Drug inhibition U Monomer I Toxic Intermediate F Fiber Mechanism provides a means of rationally designing drugs. Drug Binding site and/or mechanism is known for only a few small molecules and no peptide inhibitors.

29 How does one design a drug?!? One way is sequence homology : design a polypeptide with a matching sequence plus an inhibitory sequence. N-terminus C-terminus Rats do not get type 2 diabetes and riapp does not form fibrils. Rat amylin is a natural inhibitor. At 1:1 prevents some fibers, at 1:10 all. Monomer binding N-terminus Intercalation How does it inhibit?!?

30 Isotope labeling: 13C=18O /- 2β 1590 Frequency (cm -1 ) Frequency (cm -1 )

31 Isotope labeling: 13C=18O No Drug With Drug No Coupling /- 2β Frequency (cm -1 ) Frequency (cm Frequency -1 ) (cm -1 )

32 A13 No Drug With Drug 2β Structure Disrupted!! No Coupling

33 No Drug L16 With Drug No Coupling Structure Disrupted!! Where is beta-sheet?!?

34 L27 No Drug With Drug Structure Retained!! No Coupling Still have β-sheet

35 No Drug V32 With Drug No Coupling Structure Retained!! Still have β-sheet

36 Drug Sensitive Insensitive!! Drug Sensitive Eliminates coupling between peptides in the outermost b-sheets of the fiber, but not the inside (or turn). Not disrupting structure of the innermost core of the fiber!!

37 Monomer binding B-sheet dislocation Does not match data, since not all residues are altered equally. What is happening to outer beta-sheets?

38 N-terminus C-terminus Unlabeled Drug Labeled Drug N-terminus Intercalation

39 No Drug N-terminus Intercalation? A13 amylin + A13 Drug No Coupling (only A13 rat)

40 N-terminus denaturation Matches all the data!!! Conclusion: drug inhibits by preventing outer beta-sheet from forming.

41 A13 No Drug Data collected 6 hours after initiation. Structure Disrupted!! With Drug No Coupling 2β

42 A13 No Drug Data collected 18 hours after initiation. With Drug No Coupling Coupling returns?!?

43 A13 No Drug Data collected 18 hours after initiation. With Drug With A13 Drug Coupling returns?!?

44 N-terminal b-sheet is prevented from forming. Fiber heals itself by extruding drug. Min - Hours Hours - days By itself, rat amylin is random coil. It does not form fibers!!! 2D IR spectroscopy gives both the binding site and the mechanism. The most detailed structural information available. Without structural feedback, drug design is guesswork!!

45 Vibrational Analogue of 2D NMR 2D NMR NOESY Accurately and easily shape radio wave shapes Coherent control of nuclear spins Femtosecond 2D IR spectroscopy Challenging to create mid-ir pulse sequences Coherent control of ground state vibrations not known

46 Ground state coherence control experiments on W(CO) 6 Evolutionary algorithm to maximize ratios of peaks and therefore vibrational populational excitation by shaped pulse Optimization Function Transform limited pump pulse φ( ω) = 4 i= 1 a i sin( b ω + c i i ) 1-2 3> * > ** 1> *** 0> ******* frequency (cm -1 ) 1840

47 Ground state coherence control experiments on W(CO) 6 Evolutionary algorithm to maximize ratios of peaks and therefore vibrational populational excitation by shaped pulse Optimization Function φ( ω) = 4 i= 1 a i sin( b ω + c i i ) 3> 2> 1> 0> * ***** *** ** frequency (cm -1 ) 1840 Population inversion! (see stimulated emission)

48 Ground state coherence control experiments on W(CO) 6 Evolutionary algorithm to maximize ratios of peaks and therefore vibrational populational excitation by shaped pulse Optimization Function φ( ω) = 4 i= 1 a i sin( b ω + c i i ) 3> 2> 1> 0> * ** *** ******* frequency (cm -1 ) 1840

49 Ground state coherence control experiments on W(CO) 6 Evolutionary algorithm to maximize ratios of peaks and therefore vibrational populational excitation by shaped pulse Optimization Function φ( ω) = 4 i= 1 a i sin( b ω + c i i ) Missing an absorption 3> 2> 1> 0> ****** *** *** ** frequency (cm -1 ) 1840 Can preferentially populate vibrational levels! PRL, 2003

50 Automated 2D IR spectroscopy Method #1: Hole burning with a ps pump / fs probe (Hochstrasser, 1998) ps pump fs probe Pump Δ ij Narrowed with an etalon. Probe Want to enhance Overtone and Combination Bands in spectra.

51 Also want to control polarization of the pulse sequences. Eliminates diagonal peaks!! PNAS, 2001; JPCB, 2003

52 Mid-IR Amplitude, Phase, and Polarization Shaper Following design of Plewicki, M., et al. Appl. Opt. 2006, 45, E y (t) E(t) E x (t) 51

53 Direct mid-infrared pulse shaping Spectrum of shaped mid-infrared Intensity wavelength (nm) Amplitude 3 ns 665 ns time (μs) 500 pixels with programmable intensity and phase

54 Examples of polarization shaped pulses Two orthogonally polarized pulses 45 deg. pulse Switching pulse Time Delay / ps Time Delay / ps Circularly polarized pulse Time Delay / ps Time Delay / ps Can change shape from one laser shot to the next. Optics Exp., 2009

55 Selective vibrational excitation MnBr(CO)5 500 Transform 45 limited deg. pulse S abcd (t 1,t 2,t 3 ) = <a b c d> x R(t 1,t 2,t 3 ) Orientation response Molecular response Moving towards active manipulation of molecular vibrations to enhance infrared spectroscopy. NJP, 2009

56 3D IR spectroscopy of Ir(CO) 2 C 5 H 7 Ding and Zanni, Chem. Phys., 2007

57 2D electronic spectroscopy Light Harvesting Proteins Fleming (Berkeley) Quantum Wells Nelson (MIT) Cundiff (Boulder)

58 2D electronic spectroscopy In collaboration with Niels Damrauer at UC-Boulder Rubidium vapor Anybody with a standard pulse shaper can do these experiments!!

59 Summary Technology Development: mid-ir pulse shaping New Science: Structural mechanism of fiber formation & drug binding Future Directions: Active manipulation of vibrations & 3D IR

60

61 Graduate Students Sang-Hee Shim (Harvard) David Strasfeld (MIT) Yun Ling Wei Xiong Ann Woys Sudipta Mukherjee Emily Blanco Jennifer Laaser Lauren Buchanan Dong-Gyun Ha David Skoff Postdoc Chris Middleton Sean Moran Collaborators Raleigh, Skinner, depablo, Decatur Funding National Institutes of Health / NIDDK Packard Foundation NSF CRC, CHEM and MRSEC

62 Adding dimensions to femtosecond spectroscopy: 1D, 2D and 3D infrared and visible spectroscopies Martin Zanni, University of Wisconsin - Madison David Strasfeld

63 Adding dimensions to femtosecond spectroscopy: 1D, 2D and 3D infrared and visible spectroscopies Martin Zanni, University of Wisconsin - Madison Putin Obama David Strasfeld

64 Using this strategy to study drug binding. A natural peptide inhibitor: Rat IAPP Differs at 6 residues. Rats do not get type 2 diabetes and riapp does not form fibrils. How does it inhibit fiber formation? Where does it bind?

65 Does the fiber heal itself?!?!

66 Does the fiber heal itself?!?! With A13 Drug The drug forms fibrils!!

67 Isotope labeling: 13C=18O Ordering of folding times: #1 Val #2 A #3 L #4 A #5 A #6 V

68 Kinetics of Isotope labels Cross peak indicates that Ala25 is adopting beta-sheet secondary structure. difference intensity Diagonal peak difference slices thru w1=1574 cm-1, hiapp A25 5 min 23 min 40 min 57 min 83 min 135 min 187 min probe freq (cm-1) Probe frequency probe freq (cm-1) Cross peak kinetics match beta-sheet. As peptides aggregate, Ala25 is incorporated into beta-sheet structure with proper alignment.

69 What exactly is the mechanism? Monomer binding B-sheet dislocation N-terminus Intercalation N-terminus denaturation