Dissipation Processes of “Heat” Energy in Protein Molecules

Abstract

Vibrational energy flow in hemeproteins has been examined by picosecond time-resolved anti-Stokes resonance Raman spectroscopy. By taking advantage of the extremely short nonradiative excited state lifetime of heme in the protein (<< ps), excess vibrational energy of 20000−25000 cm⁻¹ was optically deposited selectively at the heme site. Subsequent energy relaxation in the protein moiety was investigated by monitoring the anti-Stokes Raman intensities of heme and tryptophan residues. Our results demonstrate that the present technique is a powerful tool for studying the vibrational energy flow in proteins.