Mammalian complex III heme dynamics studied with pump-probe spectroscopy and red light illuminations

O’Connor, Sean P.; Powell, Samantha M.; Rickman, John M.; Pope, Nathaniel J.; Noojin, Gary D.; Scully, Marlan O.; Denton, Michael L.; Yakovlev, Vladislav V.

doi:10.1364/boe.441118

DOE OSTI · 1842787

Mammalian complex III heme dynamics studied with pump-probe spectroscopy and red light illuminations

O’Connor, Sean P.·Powell, Samantha M.·Rickman, John M.·Pope, Nathaniel J.·Noojin, Gary D.·Scully, Marlan O.·Denton, Michael L.·Yakovlev, Vladislav V.

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Abstract

The electronic or molecular mechanisms which initiate photobiomodulation (PBM) in cells are not yet fully understood. Porcine complex III (C-III) of the electron transport chain was characterized with transient absorption spectroscopy (TAS). Then we applied our recently developed continuous wave laser coupled TAS procedure (CW-TAS) to investigate the effect of red light irradiances on the heme dynamics of C-III in its c 1 reduced state. The time constants associated with the axial ligand photodissociation were found to be 3.3 ± 0.3 ps for the oxidized state and 4.9 ± 0.4 ps for the c 1 reduced state. The analysis of the CW-TAS procedure yielded no significant changes in the C-III heme dynamics. We rule out the possibility of 635 nm CW light at 4.7 mW/cm 2 inducing a PBM effect on the heme dynamic of C-III, specifically with the photodissociation of its axial ligand.

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59 BASIC BIOLOGICAL SCIENCES complex III low-level laser low-level light photobiomodulation transient absorption spectroscopy

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O’Connor, Sean P., Powell, Samantha M., Rickman, John M., Pope, Nathaniel J., Noojin, Gary D., Scully, Marlan O., Denton, Michael L., Yakovlev, Vladislav V.. 2021-10-22. Mammalian complex III heme dynamics studied with pump-probe spectroscopy and red light illuminations. https://doi.org/10.1364/boe.441118

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