Femtosecond transient absorption spectroscopy to study the effects of low irradiance light on cytochrome c and cytochrome c reductase

摘要

Photobiomodulation (PBM) describes the enhancement of cellular functions following exposure to low irradiance visibleor NIR light. Although these effects are not well understood, PBM has been shown to enhance the synthesis of ATP so themitochondrion is the hypothesized target for the processes of photobiomodulation. More specifically, cytochromecontainingenzyme complexes of the electron transport chain (ETC) in the mitochondria are expected to be the primaryphotoabsorbers of the light thought to induce PBM. Recently, our group found light-induced changes in the activity ofcomplex Ⅲ (cytochrome c reductase) in isolated mitochondria. In this study, we use femtosecond transient absorptionspectroscopy (TAS) to study the excited state dynamics of the electronic transitions in complex Ⅲ as well as reducedcytochrome c. To investigate the potential for inducing PBM effects in these proteins, TAS experiments are performedwithout, and with, low irradiance light exposures during the scanning procedure choosing from blue (450 nm), red (635nm), and near-infrared (808 nm) laser diodes. The TAS experiments with and without light exposures during the procedureare compared to determine if PBM effects were induced. Understanding illumination induced changes in the excited statedynamics of proteins can help to better characterize the molecular processes caused by PBM and lead to a more optimizedtreatment for the enhancement of human performance and therapy.