Subfractions of membranes from calf brain synaptosomes obtained and studied by liquid-liquid partitioning.

Synaptosomes isolated from calf brain cortex were lysed and fragmented by Yeda press treatment. The obtained membranes have previously been fractionated in a counter-current distribution process using a liquid-liquid two-phase system consisting of water, dextran, Ficoll and poly(ethylene glycol) [J. Chromatogr., 358 (1986) 147]. Using the fact that there are discrete membrane populations, a rapid preparative method for isolation of the two main fractions is presented in the present work, as well as a subfractionation of one of them using liquid-liquid extraction with dextran-bound Procion yellow HE-3G. The content of several membrane constituents, i.e. protein, acetylcholinesterase, succinate dehydrogenase and ATPase, as well as opiate binding, were determined for the three fractions. Counter-current distribution of the fractions elucidates their heterogeneity and the effectiveness of the purification.