Two photon-induced electron injection from a nanotrigger in native endothelial NO-synthase

Area of Science:

• Biochemistry
• Photochemistry
• Molecular Biology

Background:

• Proteins utilize cofactors like NADPH for enzymatic activity.
• Nanotriggers (NT) are photoactive molecules designed to interact with protein cofactor sites.
• NTs possess a significantly larger two-photon cross-section than NADPH.

Purpose of the Study:

• To investigate if two-photon excitation of NT bound to protein NADPH sites can initiate enzymatic catalysis.
• To establish proof of principle for using two-photon excitation to trigger biological processes.
• To explore the potential of NT for controlled biological signaling.

Main Methods:

• Designed and utilized a photoactive nanotrigger (NT) molecule.
• Bound NT to the active site of endothelial NO-Synthase (eNOS).
• Monitored ultrafast absorption changes using one-photon (405 nm) and two-photon (810 nm) excitation.

Main Results:

• Two-photon excitation of NT initiated electron injection into eNOS's FAD cofactor.
• Catalytic cycle initiation occurred within 15±3 ps at both wavelengths.
• NT decay kinetics were influenced by the protein's hindered microenvironment compared to homogeneous solvents.
• Demonstrated that two-photon excitation can promote electron transfer.

Conclusions:

• Established that two-photon excitation can initiate enzymatic catalysis via electron transfer from NT.
• Showcased NT as a tool for synchronizing protein activity with laser pulses.
• Highlighted the potential for NT in achieving spatiotemporally resolved NO release in cells.