DETERMINATION OF ORGANOPHOSPHORUS ACID ANHYDRASE IN BLOOD

In an attempt to develop a new conceptual approach to paraoxon antagon ism by encapsulating organophosphorus acid anhydrase (OPA anhydrase) i nto carrier erythrocytes, it necessitated the spectral determination o f OPA anhydrase activity in blood. OPA anhydrase determination usually is conducted in serum or plasma. This presents a problem, because blo od contains various substances that interfere with the determination o f OPA anhydrase. This enzyme used paraoxon as the substrate, liberatin g p-nitrophenol and diethylphosphate. OPA anhydrase has a broad substr ate specificity and is capable of hydrolyzing other organophosphorus c ompounds, i.e., pesticides, nerve gases, etc. Blood OPA anhydrase acti vity was determined with paraoxon as the substrate. This reaction was terminated by adding hydrochloric acid to the reaction mixture. The p- nitrophenol then was extracted with dichloromethane, and p-nitrophenol was determined at 400 nm. The sensitivity of this method can be great ly enhanced by increasing the sample size or by using a longer reactio n time.