Example of a Detoxification Enzyme — the OPA Anhydrolases

The examples provided above give only a brief overview of the variety of enzymatic functions that alter, biotransform, and biodegrade xenobiotics. In many instances numerous enzymes are known, as in the case of the mixed function oxidases. In order to provide a concrete example of a system of detoxification enzymes that is widely distributed, we have chosen the organophosphate acid anhydrolases — enzymes that may aid in the understanding of organophosphate intoxication and may also provide a means for the detoxification and bioremediation of these materials. 

Structures of several common substrates and an inhibitor used to study the mechanisms of OPA anhydrase activity. DFP (diisopropylfluorophosphate), mipafox (N,N -diisopropylphosphorodi-amidofluoridate), tabun (N,N-dimethylethylphosphoroamidocyanidate), soman(0-l,2,2-trimethylpropylmethylphosphonofluoridate, paraoxon (diethyl 4-nitrophenyl phosphate), and parathion. 

Comparison of Several Aquatic OPA Anhydrase Activities with Typical Squid and Mazur-Type OPA Anhydrolases 

Characteristic Activity mw1 Soman/ DFP Ratio Mn2+ Stimulation Mipafox Inhibition 

Note The enzymes vary in molecular weight, reaction to ions, and in the Soman/DFP ratios. 

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