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Light-driven Enzymatic Decarboxylation
Published on: May 22, 2016
Visible light-driven O2 reduction by a porphyrin-laccase system
Theodore Lazarides1, Igor V Sazanovich, A Jalila Simaan
1Chemistry Department, University of Crete, Voutes Campus, 71003 Heraklion, Crete, Greece.
Journal of the American Chemical Society
|January 22, 2013
Summary
This study demonstrates a novel hybrid system using a zinc porphyrin photosensitizer and laccase enzyme. This system efficiently converts light energy to drive the reduction of oxygen to water, enabling new aerobic photodriven transformations.
Area of Science:
- Biochemistry and Biophysics
- Photochemistry and Catalysis
Background:
- Metalloenzymes combined with photosensitizers can drive multielectron reductions.
- Previous work focused on CO2 or HCN reduction.
Purpose of the Study:
- To investigate the combination of zinc tetramethylpyridinium porphyrin (ZnTMPyP4+) photosensitizer with laccase (a multicopper oxidase, MCO).
- To link organic molecule oxidation to the four-electron reduction of dioxygen to water.
Main Methods:
- Utilized flash photolysis to study electron transfer dynamics.
- Measured dioxygen consumption rates.
- Investigated porphyrin/enzyme ratios and excited state properties.
Main Results:
- Achieved efficient photoreduction of laccase by ZnTMPyP4+ at low ratios (1:40).
- Observed a high dioxygen consumption rate of 1.7 μmol L(-1) s(-1) at a 1:1 ratio.
- Confirmed rapid electron transfer (kET ≈ 10(7) s(-1) M(-1)) from the excited photosensitizer to the enzyme.
Conclusions:
- This work presents the first porphyrin-sensitized four-electron reduction of an MCO enzyme, leading to water formation.
- The hybrid system demonstrates suitability for aerobic photodriven transformations.
- The long-lived triplet excited state of ZnTMPyP4+ facilitates efficient electron transfer.
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