When freeze-dried brain was extracted at −4-0degrees C with dry chloroform/methanol (2:1 v/v), four of the five enzymes examined were recovered in the diethyl ether-washed residue without inactivation. By contrast, extraction with chloroform/methanol (2:1 v/v) in the presence of water destroyed activities of all the enzymes examined. The amounts of major lipids extracted were similar whether extraction was done in the absence or presence of water. The study was carried out with special interest in 2′:3′-cyclic nucleotide 3′-phosphodiesterase (EC 3.1.4.37), which is firmly bound to the membrane structures of brain white matter.
