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THz-Spectroscopy of Biological Molecules
T R Globus1, D L Woolard, T Khromova
1University of Virginia, Charlottesville, VA.
Journal of Biological Physics
|January 25, 2013
Summary
Terahertz spectroscopy reveals unique vibrational fingerprints in DNA and RNA. These terahertz phonon modes, linked to molecular vibrations, offer sequence-specific insights into biomacromolecules.
Area of Science:
- Biophysics
- Molecular Spectroscopy
- Materials Science
Background:
- Terahertz (THz) frequency absorption spectra of DNA molecules are linked to low-frequency internal helical vibrations.
- Identifying THz phonon modes in biological materials is challenging due to experimental difficulties.
Purpose of the Study:
- To demonstrate the possibility and utility of measuring THz absorption spectra of DNA and related biological materials.
- To confirm that observed absorption features are intrinsic properties determined by phonon modes.
Main Methods:
- Fourier-Transform Infrared (FTIR) spectroscopy in the terahertz frequency range.
- Normal mode analysis to predict absorption spectra of polynucleotide RNA Poly[G]-Poly[C].
- Interference spectroscopy to extract absorption characteristics and study orientation dependence.
Main Results:
- Spectra of different DNA samples showed numerous modes with sequence-specific uniqueness.
- A correlation was found between calculated and experimentally observed spectra of RNA polymers, confirming internal vibration modes.
- Strong anisotropy of terahertz characteristics was demonstrated in aligned DNA and polynucleotide films.
Conclusions:
- Terahertz absorption spectra provide valuable, sequence-specific information about DNA and RNA macromolecules.
- The fundamental nature of observed resonance structures is attributed to internal vibration modes within macromolecules.
- THz spectroscopy is a viable and fruitful technique for characterizing biological materials.
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