Triplet Energy Migration in Cytoskeletal Polymers

Area of Science:

• Biophysics
• Molecular Biophysics
• Computational Biology

Background:

• Dexter energy transfer (DET) facilitates triplet electronic state energy transfer, crucial for applications like photovoltaics and photodynamic therapy.
• The capacity for triplet energy migration through aromatic residues in protein polymers remains largely unexplored.

Purpose of the Study:

• To computationally investigate Dexter energy transfer (DET) rates between aromatic residues in cytoskeletal polymers.
• To compare triplet energy migration with singlet energy migration via Förster resonance energy transfer (FRET) in these biological systems.

Main Methods:

• Computational modeling of Dexter energy transfer (DET) rates.
• Analysis of interaromatic residue couplings within microtubules, actin filaments, and vimentin.
• Calculation of triplet and singlet energy diffusion lengths.

Main Results:

• Dexter couplings within protein subunits can be comparable to those in organic electronics.
• Interaromatic residue Dexter couplings are generally weak (<10^-3 eV), resulting in short triplet energy diffusion lengths (0.5–6.1 Å).
• Singlet energy diffusion lengths via FRET are significantly longer (8.6–12.4 Å).

Conclusions:

• Singlet energy migration via FRET is the dominant mechanism in cytoskeletal polymers.
• Triplet energy migration via DET is highly restricted in these protein filaments.
• Findings provide insights into energy transfer dynamics within biological polymers.