Vanadium- and Phosphate-metabolising Enzymes

haloperoxidase activity of vanadate-inhibited phosphatases phosphatase activity of apo-haloperoxidases  

structural vanadium analogues of phosphate esters and anhydrides. 

Top row schematic representation of the hydrolysis of the phospho-ester bond as catalysed by a phosphatase with a histidine in the active site, including the pentacoordinated intermidiate state. Bottom row the two-step mechanism for the cleavage of the phospho-diester bond by ribonucleases, showing the transphosphorylation to cyclic ribose phosphate (step 1) and hydrolysis (step 2). 

For an overview of The power of vanadate in crystallographic investigations of phosphoryl transfer enzymes , see ref. 59a. 

Four examples of structurally characterised, vanadate-inhibited phosphorylation enzymes working on the hydrolysis of phospho-ester bonds in nucleotides I, the vanadate-uridine complex of bovine pancreatic ribonuclease-A II, the vanadate complex of ribonuclease-Tj from the fungus Aspergillus oryzae-. III, the vanadate-uridine complex of cyclic nucleotide phosphodiesterase from the cruciferous plant Arabidopsis thaliana-, IV, human tyrosyl-DNA phosphodiesterase (Ur = uridine). 

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