Coordination environment changes of the vanadium in vanadium-dependent haloperoxidase enzymes

Area of Science:

• Biochemistry
• Bioinorganic Chemistry
• Enzymology

Background:

• Vanadium-dependent haloperoxidases (VHPs) catalyze essential oxidation reactions.
• VHPs employ a conserved active site coordination geometry despite diverse protein structures.
• Understanding VHP active site chemistry is crucial for enzyme mechanism elucidation.

Purpose of the Study:

• To compare the coordination chemistry of vanadium in VHPs using data mining.
• To analyze the dynamic changes in vanadium coordination geometry during the catalytic cycle.
• To investigate the unique features of the VHP active site compared to small molecule models.

Main Methods:

• Data mining of V-containing haloperoxidase structures.
• Comparative analysis of coordination geometries.
• Investigation of catalytic cycle intermediates.

Main Results:

• Vanadium coordination geometry shifts between trigonal bipyramidal and distorted square pyramidal during catalysis.
• A proton-relay system and dynamic vanadium coordination facilitate catalysis.
• VHP active site geometries differ significantly from crystallized small molecules and model compounds.
• The peroxidovanadium(V) geometry in VHPs has no known small molecule structural analog.

Conclusions:

• The active site of vanadium haloperoxidases is tightly regulated, exhibiting dynamic coordination geometry changes.
• The unique coordination environment and proton-relay system distinguish VHP catalysis.
• Further research into small molecule mimics with similar geometries is warranted.