title: Change of catalytic properties of erythrocyte acetylcholinesterase after binding to lecithin liposomes.
abstract: Phosphatidylcholine and phosphatidylserine + phosphatidylcholine liposomes were prepared with cholate and erythrocyte acetylcholinesterase (EC 3.1.1.7). Dipalmitoyllecithin- and egg lecithin-acetylcholinesterase complexes exhibit an affinity for acetylthiocholine different from that of the free enzyme. The binding to lecithin apparently abolishes the excess substrate inhibition of acetylcholinesterase; the affinity constants of acetylthiocholine, acetylcholine and acetylcarnitine for the lecithin-bound enzymes are higher than the ones found for the free enzyme. Binding to lecithin decrease the optimum pH value for acetylcholinesterase, increase the resistance of the enzyme to heat denaturation and reduces the extent of activation by Ca2+.
mesh_terms: D000108:Acetylcarnitine / Q000378:metabolism; D000110:Acetylcholinesterase / Q000097:blood*; D000122:Acetylthiocholine / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002384:Catalysis; D002417:Cattle; D002800:Cholinesterase Inhibitors; D004912:Erythrocytes / Q000201:enzymology*; D008081:Liposomes; D010713:Phosphatidylcholines / Q000494:pharmacology*; D011663:Pulmonary Surfactants / Q000494:pharmacology; D013379:Substrate Specificity
chemical_list: D002800:Cholinesterase Inhibitors; D008081:Liposomes; D010713:Phosphatidylcholines; D011663:Pulmonary Surfactants; D000122:Acetylthiocholine; D000108:Acetylcarnitine; D000110:Acetylcholinesterase; D002118:Calcium