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Abstract Engineered heme protein biocatalysts provide an efficient and sustainable approach to develop amine‐containing compounds through C−H amination. A quantum chemical study to reveal the complete heme catalyzed intramolecular C−H amination pathway and protein axial ligand effect was reported, using reactions of an experimentally used arylsulfonylazide with hemes containing L=none, SH−, MeO−, and MeOH to simulate no axial ligand, negatively charged Cys and Ser ligands, and a neutral ligand for comparison. Nitrene formation was found as the overall rate‐determining step (RDS) and the catalyst with Ser ligand has the best reactivity, consistent with experimental reports. Both RDS and non‐RDS (nitrene transfer) transition states follow the barrier trend of MeO−−
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Mammalian complex III heme dynamics studied with pump-probe spectroscopy and red light illuminations
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 c1reduced 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 c1reduced 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/cm2inducing a PBM effect on the heme dynamic of C-III, specifically with the photodissociation of its axial ligand.
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- Award ID(s):
- 2013771
- PAR ID:
- 10307936
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Biomedical Optics Express
- Volume:
- 12
- Issue:
- 11
- ISSN:
- 2156-7085
- Format(s):
- Medium: X Size: Article No. 7082
- Size(s):
- Article No. 7082
- Sponsoring Org:
- National Science Foundation
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