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

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

doi:10.1364/BOE.441118

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

Biomed Opt Express. 2021 Oct 22;12(11):7082-7091. doi: 10.1364/BOE.441118. eCollection 2021 Nov 1.

Authors

Sean P O'Connor¹, Samantha M Powell^{2

3}, John M Rickman⁴, Nathaniel J Pope^{4

5}, Gary D Noojin⁴, Marlan O Scully^{1

6}, Michael L Denton^{7

8}, Vladislav V Yakovlev^{1

9

10}

Affiliations

¹ Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA.
² National Research Council Postdoctoral Fellow, JBSA Fort Sam Houston, TX 78234, USA.
³ Currently with the Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
⁴ SAIC, JBSA Fort Sam Houston, TX 78234, USA.
⁵ ORISE Postdoctoral Fellow, JBSA Fort Sam Houston, TX 78234, USA.
⁶ Department of Physics, Baylor University, Waco, TX 76798, USA.
⁷ Air Force Research Laboratory, JBSA Fort Sam Houston, TX 78234, USA.
⁸ michael.denton.10@us.af.mil.
⁹ Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA.
¹⁰ yakovlev@tamu.edu.

Abstract

The electronic or molecular mechanisms that initiate photobiomodulation (PBM) in cells are not yet fully understood. The porcine complex III (C-III) of the electron transport chain was characterized with transient absorption spectroscopy (TAS). We then 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 c₁ reduced state. The time constants were found to be 3.3 ± 0.3 ps for vibrational cooling of the oxidized state and 4.9 ± 0.4 ps for rebinding of the photodissociated axial ligand of the c₁ 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/cm² inducing a PBM effect on the heme dynamic of C-III, specifically with the photodissociation of its axial ligand.