Esterases of triatoma infest ans and its relationship with the metabolism of organophosphorus insecticides

1.1.The activity of eserine-resistant esterases and their inhibition by 10−5M paraoxon in subcellular fractions of thorax and abdomen of Triatoma infestans were examined. Most of the activity per insect was found in the soluble fractions. The abdomen was the richer part of the body in esteratic activity.2.2. The influence of bivalent cations on the activity of the esterases was studied. Ca2+, Mn2+ and Co2+ activated hydrolases appear to be present in T. infestans.3.3. Disc electrophoresis of homogenates from thorax or abdomen resolved 9 bands with activity toward α-naphthylacetate. These were characterized as: 6 carboxyesterases, 1 acetylesterase, 1 arylesterase and 1 superimposed mixture of different types of esterases on the top.4.4. The hydrolytic activity of each band toward [14C] parathion and [14C] paraoxon was determined. Splitting of both substrates was only performed by the arylesterase corresponding to band IX.