Dresden 2003 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 21: POSTER B
CPP 21.6: Poster
Tuesday, March 25, 2003, 19:00–21:00, ZEU/250
Photodissociation of carboxymyoglobin studied by Four-wave mixing techniques and THz-Spectroscopy — •M. Walther1,2, V. Raicu1, R. J. D. Miller1, B. M. Fischer2, H. Helm2, and P. Uhd Jepsen2 — 1Departments of Physics and Chemistry, University of Toronto, 80 St. George St., Toronto, Canada — 2Physikalisches Institut, Albert-Ludwigs-Universität, Hermann-Herder Str. 3, 79104 Freiburg
Protein dynamics and ligand escape of carboxymyoglobin (MbCO) in solution has recently been studied by 4-wave mixing spectroscopy [1]. Embedding the MbCO in trehalose glass freezes protein relaxation modes but preserves its internal mobility and function [2].
In one experiment we investigate the dynamics of MbCO in trehalose after photoexcitation by transient phase-grating spectroscopy. This technique is highly sensitive to changes of the refractive index due to thermal heating or protein response. We are able to measure the branching of the pump energy into bond breaking and thermal heating and thereby obtain the binding energy of the ligand to the heme iron.
In a second experiment we investigate the embedded protein samples in the far-infrared (FIR) spectral region. We use THz time-domain spectroscopy to demonstrate that sugar glasses like amorphous trehalose have a featureless spectrum in the FIR and are a suitable solvent enabling the observation of low-frequency molecular vibrations.
This work was supported by the DFG in SFB 276 C14.
[1] J. Ogilvie et al, J. Phys. Chem. B, 106, 10460 (2002)
[2] S. J. Hagen et al, Science 269, 959 (1995)