Choline Acetyltransferase from Rat Brain

摘要: Abstract The localization, purification, and some enzymatic properties of choline acetyltransferase from rat brain were studied. Most assays performed with a specific radiometric micromethod. Solubilization the enzyme was examined after homogenization cerebral cortices by means which disintegrate nerve endings. In isotonic KCl recovered in solution. more dilute adsorbed progressively but reversibly to particles, especially at low pH. subcellular localizations acetylcholine formed choline-14C vivo further gentle cortices. Subcellular fractions prepared density gradients sedimented NaCl desorb transferase microsomes. From homogenates, 56% total 60% acetylcholine-14C found hypotonic homogenates (in endings are lysed) solution, whereas 3H-Acetylcholine added homogenizing medium remained It is concluded that synthesized cytoplasm then incorporated into synaptic vesicles. purified whole brains activity (Vmax) 0.727 µmole product min-1 mg protein-1 38°. final preparation free deacylases, acetylcholinesterase, carnitine acetyltransferase. By gel filtration molecular weight about 50,000; other studies indicated possesses essential —SH groups, protein quite cationic, it soluble 0.1 mm buffers. Fifteen salts appeared activate enzyme. Michaelis constants for forward reaction determined; each substrate reduced affinity substrate. enzyme-catalyzed reversible an apparent equilibrium constant 514. possible amount regulated mass action.