Abstract
The activity of cholinesterase in human serum was determined amperometrically using a dialysis membrane-covered electrode without any interference from such compounds in serum as uric acid and proteins.
The anodic current due to the S-butyrylthiocholine iodide, the substrate, appeared in the potential range more positive than+350mV, while that due to thiocholine, the product, appeared more positive than+100mV and reached a limit of approximately 400mV at pH 7.3. The current derived from a solution containing butyrylthiocholine and cholinesterase at 300 mV and pH 7.3 increased linearly with time and the increase in current per min was proportional to the amount of cholinesterase. On the basis of this result, the activity of cholinesterase in serum was determined in a similar manner as above. Relative standard deviation (RSD) for this measurement (n=5) was 2.65%. The activity of cholinesterase measured by this method agreed well those made by a photometric method using cholineoxidase (r=0.998).
