Subcellular distribution op neurotoxic esterase activity in lamb and mouse brain

Abstract
Brain tissue samples of mice (7.6 g) from 25 mouse brains and lamb (25 g) were homogenized and subcellular fractions prepared to assay the distribution of neurotoxic esterase (NTE) activity. The specific inhibitor, N,N-diisopropylphosphorodiamidic fluoride (mipafox) [an insecticide] was synthesized and purified. Maximum specific activity of NTE was reached in the microsomal fraction (110,000 g) while the enzyme activity in the soluble fraction (110,000 g) was extremely low. This subcellular distribution of NTE activity in mammal brains is an original contribution. Brain microsomal fraction may be a more reliable source for the highest activity of NTE. The specific activity of NTE of lamb brain was much higher than that of mouse brain. This might help interpretation of the characteristic species variation in susceptibility to NTE inhibitors which are known to be potent delayed neurotoxic agents.