Biomolecular Dynamics Studied by Vibrational Spectroscopy
Since A.S. Davydov1, 2 proposed the soliton model for the alpha-helix of a protein many theoretical approaches have appeared. These are covered by other reviews in this book and they shall not be referenced here. The Davydov work was an inspiration for a more general view on the importance of nonlinear dynamics in many different fields. However, a direct evidence for the existence of Davydov solitons is very difficult to obtain. A theoretical explanation of protein dynamics in terms of Davydov solitons was published by Scott3. Studies of the carbonyl-stretching vibrations of acetanilide (ACN) and N-methylacetamide (NMA) reveal evidence of effects due to nonlinear dynamics4–6. ACN and NMA are examples of model compounds for real proteins. A direct correlation between observed spectra and theories are much more difficult to obtain for macromolecules with a biological significance. Experimental studies in the amide-I region will mainly be covered by other contributors to this book7. In the present paper is shown how the, low-frequency part of the vibrational spectrum (10–400 cm−1) can be of importance in breaking of hydrogen bonds through a coupling to energy trapped in vibrational modes. Furthermore the carbonyl-stretching vibration of liquid formamide in different Raman scattering configurations will be discussed.
KeywordsVibrational Spectroscopy Real Protein Davydov Soliton Formamide Molecule Simple Amide
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