Biochemical synaptosomal fractions from

Biochemical characteristics of the "Nerve ending fraction" and of the "Synaptosomal fraction", obtained from calf brain. Ganglio-sides are expressed as nmoles bound N-acetylneuraminic acid enzyme activities in milli International Units ( 1 nmole transformed substrate min at 37°C - 30° for NADH-, and NADPH-Cyt C reductase and LDH). The data shown, referred to 1 g starting fresh tissue, are the mean values of 6 experiments the S. E. was in all cases lower than + 10 % of the mean values. 

Fig. 2. Binding of ChAc ( ) and protein (o) to membranes from synaptosome fraction at various ionic strengths. A, Gelfiltration of membranes and ChAc on Sephadex columns equilibrated with 1 mmole sodium phosphate buffer plus NaCI to give final ionic strength and pH 7.2 and B, Dilution of sample with water to final ionic strength 0.015 and pH 7.2. (Reproduced from Biochem. J. (1968),...

Apnson M H and McBnde W. ] (1973) Evidence for the net accumulation of glycine into a synaptosomal fraction isolated from the telencephalon and spinal cord of the rat Life Set 7, 583-590. Baker P F and Glitsch H G (1975) Voltage-dependent changes in the permeability of nerve membranes to calcium and other divalent cations Phil, Trans Roy Soc (B) 270, 389-409 Beart P. M., Kelly]. S, and Schon F. (1974) 7-Aminobutyric acid uptake in the rat peripheral nervous system, pineal, and posterior pituitary Biochem Soc Trans 2, 26 268 Benjamin A M and Quastel ] H. (1972) Locations of amino acids in brain slices from the rat. Tetrodotoxm-sensitive release of amino acids Biochem J 128, 631-646... 

An important aspect of the preparation and isolation of subcellular particles from brain regions is the criteria by which purity is assessed. Electron microscopy of the various subcellular fractions can provide among the best pieces of evidence for the presence in the preparation of the organelles or subcellular fragments of interest. However, a number of biochemical markers (usually enzymes) that have been established to be present in certain fractions can also be assayed to demonstrate the enrichment of the organelle of interest. For instance, acetylcholinesterase is a common marker for synap-tosomes dopamine-P-hydroxylase is a marker for catecholamine storage vesicles within the synaptosome and cytochrome c oxidase is a marker for mitochondria. Most of the enzymatic markers can be assayed routinely. 

Fig. 3. Distribution of non-occluded ( ) and occluded ill ID ChAc in fractions separated by discontinuous density gradient centrifuging. The blocks correspond to the fractions 0-1 described by Whittaker et at. (1964). A, Suspension of hypo-osmotically treated synaptosomes and B, After binding of soluble ChAc to synaptosome membranes. (Reproduced from Biochem. J. (1968), F.

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