Observation of dynamic oxygen release in hemoglobin using surface enhanced Raman scattering

Photoinduced oxygen dynamics in hemoglobin is monitored by surface enhanced resonant Raman spectroscopy (SERRS) using silver colloids. The spectra are characterized by massive transient amplifications which we assign to a charge-transfer mechanism during the opening of the heme-pockets in the release of oxygen. This transient lifts the selection rule specificity of normal Raman active modes and allows for the full density of states of the hemes to be observed. The amplification of specific forbidden modes is controlled by the orientation alignment of individual molecules in proximity with the colloid surface. We propose that the technique can be used to monitor oxygen release in single proteins.