A Midgut Digestive Phospholipase A in Larval Mosquitoes, and .

Phospholipase A (PLA) is a secretory digestive enzyme that hydrolyzes ester bond at position of dietary phospholipids, creating free fatty acid and lysophospholipid. The free fatty acids (arachidonic acid) are absorbed into midgut cells. and digestive PLA was characterized using a microplate PLA assay. The enzyme showed substantial activities at 6 and 8 g/l of protein concentration with optimal activity at 20 and 25 g/l of substrate concentration in and , respectively. PLA activity from both mosquitoes increased in a linear function up to 1 hour of the reaction time. Both enzymes were sensitive to pH and temperature. PLA showed higher enzyme activities in pH 8.0 and pH 9.0 from and , respectively, at 40°C of incubation. The PLA activity decreased in the presence of 5 mM and 0.5 mM site specific PLA inhibitor, oleyloxyethylphosphorylcholine. Based on the migration pattern of the partially purified PLA on SDS-PAGE, the protein mass of PLA is approximately 20-25 kDa for both mosquitoes. The information on PLA properties derived from this study may facilitate in devising mosquitoes control strategies especially in the development of inhibitors targeting the enzyme active site.