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Updated: May 30, 2025

Light-driven Enzymatic Decarboxylation
Published on: May 22, 2016
Protein-Driven Electron-Transfer Process in a Fatty Acid Photodecarboxylase
Giacomo Londi1, Giacomo Salvadori2, Patrizia Mazzeo1
1Department of Chemistry and Industrial Chemistry, University of Pisa, 56124 Pisa, Italy.
Fatty acid photodecarboxylases from Chlorella variabilis (CvFAPs) are rare photoenzymes. This study reveals their light-induced decarboxylation mechanism, identifying key structural changes and energy landscapes for protein engineering.
Area of Science:
- Biochemistry
- Photochemistry
- Enzymology
Background:
- Naturally occurring photoenzymes are rare.
- Fatty acid photodecarboxylases (CvFAPs) from Chlorella variabilis catalyze light-induced fatty acid decarboxylation.
- CvFAPs convert free fatty acids into n-alkanes via redox-neutral reactions.
Purpose of the Study:
- To elucidate the atomistic mechanism of CvFAP photoactivation.
- To characterize the structural and energetic landscape of electron transfer.
- To investigate the role of specific mutations on enzyme function.
Main Methods:
- Hybrid quantum mechanics/molecular mechanics (QM/MM) approach.
- Polarizable embedding scheme for accurate electronic structure.
- QM/MM molecular dynamics simulations.
Main Results:
- Identified key structural changes in the active site upon photoexcitation.
- Determined the energetic landscape of forward electron transfer (fET).
- Observed spontaneous water rearrangement and substrate twisting facilitating fET.
- R451K mutant showed resilience to reduced electronic coupling.
- Decarboxylation occurs within picoseconds with a low energy barrier (~0.1 eV).
Conclusions:
- Provided an atomistic characterization of CvFAP photoactivation.
- Structural modifications drive downhill fET.
- The enzyme's mechanism exhibits resilience to mutations affecting electronic coupling.
- Findings can guide future protein engineering efforts for improved photobiocatalysts.
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