Kuznetsova_1988_Ukr.Biokhim.Zh_60_35

Sodium chloride, phosphate buffer and ethanol were studied for their effect on butyryl cholinesterase hydrolysis rate of acetylcholine, acetylthiocholine, butyrylthiocholine and nonion substrate of indophenylacetate. The concentrations of 1.10(-2) = 1.10(-1) M of sodium chloride activated enzymatic hydrolysis of ion substrates at the concentrations lower than 1.10(-4) M but sodium chloride is a competitive inhibitor at higher concentrations. Phosphate buffer also activates substrates enzyme hydrolysis at the concentrations of 2.10(-4) M and lower, but it inhibits incompetitively the nonion substrate indophenylacetate hydrolysis. Ethanol activates butyrylthiocholine hydrolysis and is a competitive inhibitor in acetylthiocholine and indophenylacetate hydrolysis. The observed effects are discussed on the assumption of two forms of butyrylcholinesterase E' and E" existence. These two forms are determined by different kinetic parameters and are in equilibrium.