We analyzed molecular and enzymatic properties of three cholinesterases (ChEs; ClAChE1, ClAChE2 and ClSChE) from Cimex lectularius. The ClAChE1 and ClAChE2 were generally present as a membrane-anchored dimeric insoluble form in the brain and ganglia. In the case of ClSChE, monomeric and dimeric soluble forms were observed. To investigate enzymatic properties, three ChEs were functionally expressed using baculovirus expression system. ClAChE1 revealed a significantly higher activity than ClAChE2 to acetylthiocholine iodide (ATChI) substrate. Kinetic analysis using two choline substrates (ATChI and butyrylthiocholine iodide) demonstrated that ClAChE2 had higher catalytic efficiency but lower substrate specificity than ClAChE1. Inhibition assay was conducted by using three inhibitors (BW284C51, eserine, Iso-OMPA) and two insecticides (chlorpyrifos-methyl and carbaryl). Two ClAChEs revealed high sensitivities to BW284C51, eserine, chlorpyrifos-methyl and carbaryl, but were not sensitive to Iso-OMPA. This inhibition profile confirmed that both ClAChEs are categorized as ChEs. Interestingly, the salivary specific cholinesterase did not show any measurable activities to choline substrates, confirming its non-synaptic function in C. lectularius

• Chae Eun Hwang(Department of Agricultural Biotechnology, Seoul National University)
• Keon Mook Seong(Research institute for Agricultural and Life sciences, Seoul National University)
• Deok Ho Kwon(Department of Agricultural Biotechnology, Seoul National University)
• Young Ho Kim(Research institute for Agricultural and Life sciences, Seoul National University)
• Jae Young Choi(Department of Agricultural Biotechnology, Seoul National University)
• Yeon Ho Je(Department of Agricultural Biotechnology, Seoul National University)
• Si Hyeock Lee(Department of Agricultural Biotechnology, Seoul National University, Research institute for Agricultural and Life sciences, Seoul National University)