Time-Resolved Raman Mapping of Energy Flow in Proteins

We have summarized our work on time-resolved Raman mapping of protein energy flow. It is not yet clear how energy migrates through proteins. Anti-Stokes ultraviolet resonance Raman (UVRR) spectroscopy has been used to develop techniques to address the characteristics of energy flow. One of the key advantages of UVRR spectroscopy is its high sensitivity to aromatic side chains due to resonance Raman enhancement. This enhancement allows you to observe specific sites on large protein molecules at the level of a single amino acid residue. In addition, anti-Stokes intensity is a selective probe of vibrationally excited populations. These advantages make time-resolved anti-Stokes UVRR spectroscopy ideal for studying the vibrational energy flow of proteins. Our studies on heme proteins demonstrated that the major channel of the excess energy transfer is not through covalent bonds of the main chain but through van der Waals atomic contacts between heme and the probe residue. It was also shown that anti-Stokes spectra of tryptophan residues serve an excellent spectroscopic “thermometer” in terms of high sensitivity and straightforward interpretation.