SOLUBILIZATION OF NEUROPATHY TARGET ESTERASE AND OTHER PHENYL VALERATE CARBOXYLESTERASES FROM CHICKEN EMBRYONIC BRAIN BY PHOSPHOLIPASE A(2)

Membrane-bound neuropathy target esterase (NTE) and associated phenyl valerate carboxylesterases were solubilized from chicken embryo brain by phospholipase A(2). Phospholipase A(2) from bee or cobra (Naja) ven oms were the most effective preparations in solubilizing brain NTE and other phenyl valerate carboxylesterases. Phospholipase C and several proteinases (endoproteinase, pronase E, proteinase K, thermolysin, try psin) did not solubilize brain membrane-bound carboxylesterases but re duced their activity, NTE solubilization by phospholipase A(2) did not affect its apparent K-m and V-max for the substrate phenyl valerate o r the susceptibility of phenyl valerate carboxylesterases to inhibitio n by paraoxon and mipafox, NTE thermal stability diminished after the treatment of brain membrane fragments with phospholipase A(2).