Acetylcholinesterase from sarcoplasmic reticulum of white muscle

1. Two membrane fractions were separated from rabbit white muscle SR by discontinuous sucrose gradient. 2. Both crude and membrane fractions were shown to contain AChE, Ca2+-stimulated and Ca2+- independent ATPase activities. 3. 1% W/V Triton X-100 solubilized most of the AChE and Ca2+-stimulated ATPase but the Ca2+- independent ATPase was poorly solubilized. 4. AChE was sensitive to BW284c51, non-sensitive to ethopropazine and presented inhibition by excess of the substrate, ATCh. 5. Polyacrylamide gel electrophoresis from Triton-treated crude SR revealed several bands of AChE and ATPase activities. 6. SDS-gel electrophoresis from crude SR showed two polypeptides specifically labelled with [3H]DFP.