Carboxylesterases from Boophilus microplus hydrolyze trans-permethrin

An esterase which hydrolyzes the ester bond of trans-permethrin has been partially purified from homogenates of larvae of the cattle tick. The final (gel filtration) step showed two distinct peaks of p-nitrophenylbutyrate-hydrolyzing activity. The trans-permethrin-hydrolyzing activity of the lower-molecular-weight enzyme cochromatographed with the p-nitrophenylbutyrate-hydrolyzing activity of that enzyme. Little trans-permethrin hydrolysis was observed in the high-molecular-weight peak. The yield of the low-molecular-weight enzyme increased on extraction of the homogenates with Triton X-100. Inhibition studies using the low-molecular-weight enzyme and trans-permethrin as substrate indicated that hydrolysis was due largely to a carboxylesterase (EC 3.1.1.1).