Organofluorophosphate-hydrolyzing activity in an estuarine clam, Rangia cuneata.

1. The bivalve Rangia cuneata can enzymatically detoxify the organophosphorus acetylcholinesterase inhibitors DFP and soman. 2. Digestive gland homogenates contained Mazur-type DFPases based on response to Mn2+ ions, and relative rates of DFP: soman hydrolysis. Squid-type DFPase contributed little to the total organophosphate acid (OPA) anhydrase activity of these preparations. 3. The natural substrate(s) and physiological role(s) of OPA anhydrase in R. cuneata has yet to be determined; however, DFPase specific activity was pronounced in the digestive gland, the primary organ involved in bioconcentration and biotransformation of xenobiotics, and in the gills, which are in continuous contact with water-borne chemicals.