Distribution of sodium-plus-potassium-stimulated adenosine-triphosphatase activity in isolated nerve-ending particles.
1. A rapid method for the isolation of nerve-ending particles from brain is described. This involved the centrifugation of the large-granule fraction over a discontinuous density gradient consisting of 3% (w/v) and 13% (w/v) Ficoll dissolved in 0.32m-sucrose. The results of the biochemical as well as morphological identification of nerve-ending particles are given. 2. Approx. 20% of the (Na(+)+K(+))-stimulated adenosine-triphosphatase activity originally present in the cerebral grey-matter suspension was recovered in the fraction consisting principally of large nerve-ending particles (approx. 1mu in diameter). The activity of the adenosine triphosphatase/mg. of protein in the nerve-ending fraction approximated to that in the small-granule fraction after the treatment with glycol ether diamine-tetra-acetic acid. The conclusion was drawn that the synaptic structure, supposedly the limiting membrane of the nerve-ending particle, is one of the feasible sites of localization of the (Na(+)+K(+))-stimulated adenosine-triphosphatase activity in cerebral tissues. Adenosine triphosphatase in purified cerebral mitochondria was not stimulated by Na(+). 3. No qualitative differences were found between the (Na(+)+K(+))-stimulated adenosine-triphosphatase activities exhibited by the nerve-ending particles and by the cerebral small-granule fraction with respect to pH-dependence, cation requirements and susceptibility to ouabain.
D000109:Acetylcholine; D000217:Acyltransferases / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002540:Cerebral Cortex; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008861:Microsomes / Q000201:enzymology*; D008928:Mitochondria / Q000201:enzymology*; D009411:Nerve Endings / Q000166:cytology*; D011188:Potassium; D012964:Sodium; D013347:Subcellular Fractions; D013385:Succinate Dehydrogenase / Q000378:metabolism
D012964:Sodium; D007770:L-Lactate Dehydrogenase; D013385:Succinate Dehydrogenase; D000217:Acyltransferases; D000251:Adenosine Triphosphatases; D000109:Acetylcholine; D011188:Potassium