Purification and characterization of neuropathy target esterase (NTE) from rat brain

Neuropathy target esterase (NTE) is an integral membrane protein in vertebrate neurons and a member of a novel family of putative serine hydrolases. Neuropathic organophosphates react covalently with the active site serine residue of NTE, causing degeneration of long axons in spinal cord and peripheral nerves which becomes clinically evident 1-3 weeks after exposure to OPs, hence termed as organophosphate induced delayed neuropathy. The present study reports the isolation and characterization of NTE protein from rat brain. Rat brain microsomes were solubilized with phospholipase A2 and they were fractionated by gel filtration chromatography in S-300 column. The sample was eluted in buffer containing polyoxyethylene W1 detergent, which yielded an active fraction of 200 kDa. The most enriched NTE active fraction was further purified by 3-9'-mercaptononylthio-1,1,1-trifluoropropan-2-one bound to sepharose CL4B. The SDS-PAGE confirmed the 155-kDa protein as the most likely candidate for NTE. Database searching of rat N-terminal protein revealed homology with variety of polypeptides from different organisms and suggested that NTE protein has function beyond the nervous system and mediates a biochemical reaction highly conserved through evolution.