Characteristics of Fish Activities

Hogan and Knowles (1968) examined the OPA anhydrases of liver homogenates from the bluegill sunfish, Lepomis macrochirus, and the channel catfish, Ictalarus punctatus. Initially, a 1.5% (w/v) homogenate of the excised livers from each species was determined to hydrolyze 10 2M concentrations 

Bluegill and catfish were both able to hydrolyze DFP, dichlorvos, and dimethyl 2,2,2-trichloro-l-n-butyryloxyethyl phosphonate (butonate). Catfish enzymes were also able to hydrolyze paraoxon and methyl 3-hydroxy-alpha-cronate dimethyl phosphate (mevinphos) although at a very slow rate. Kms calculated for the enzymes of both species indicated that each had a greater affinity for DFP than dichorvos. Sulfhydryl reagents and Cu2+ were found to inhibit the enzymatic activity of both organisms. Paraoxon had no effect. Cleavage products were identified as dimethyl phosphate and 2,2-dichloroacetaldehyde from dichlorovos hydrolysis and diisopropyl phosphate from the hydrolysis of DFP. 

The fish Electrophorus was examined by Hoskin et al. (1984) and found to have an activity that hydrolyzes soman faster than DFP and to be stimulated by Mn2+. This activity may be similar to those of catfish and bluegill. 

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