Studies on microbial cholinesterase. II. Purification and characterization of the cholinesterase of Pseudomonas aeruginosa A-16.

The cholinesterase of Pseudomonas aeruginosa A-16 was purified approximately 11,150fold with an overall recovery of 15.2% and proved to be homogeneous by electrophoresis, ultracentrifugation and chromatography.The molecular weight of the enzyme was determined as approximately 30,000 by equilibrium centrifugation and gel filtration methods.The sedi mentation coefficient, S20,1 was determined to be 3.3 S. Isoelectric focusing electrophoresis with carrier ampholite revealed that the enzyme had an isoelectric point around pH8.1.The purified cholinesterase, which was considered to be an acetylcholinesterase from its substrate specificity, hydrolyzed acetylthiocholine and acetylcholine at the highest rates among the various esters tested.The estimated values of Km at pH 7.5 and 25°C were 1.5 x 10-4 tit for acetylthiocholine and 1.9 x 10-4 M for acetylcholine.The enzyme also hydrolyzed the acetyl and propionyl esters of several aliphatic and aromatic alcohols at a lower rate which was entirely dependent on the properties of the alcohol moiety of those esters.