Purification and characterization of butyrylcholine-hydrolyzing enzyme from Pseudomonas polycolor

A butyrylcholine-hydrolyzing enzyme (EC 3.1.1.-) of Pseudomonas polycolor IFO 3918 was purified approximately 9270-fold with a recovery of 9.9% by use of chromatographic techniques. The enzyme preparation appeared to be homogeneous when subjected to electrophoretic and ultracentrifugational analyses. The molecular weight was determined as approximately 59 000 by gel filtration. Isoelectric focusing electrophoresis revealed that the enzyme had an isoelectric point around pH 5.1. The enzyme catalyzed the hydrolysis of butyrylcholine with the maximum activity among various esters tested, and split benzoylcholine, propionylcholine and some aliphatic esters, but did not attack acetylcholine. The estimated value of Km at pH 7.5 and 25°C was 7 · 10−4 M for butyrylcholine. The enzyme was irreversibly inhibited by organophosphorus compounds and carbamates, such as diisopropylphosphofluoridate and eserine. The enzyme was inhibited by some compounds, such as atropine and quinidine. Quaternary ammonium salts showed an inhibitory effect on the enzyme resemblng co-operation inhibition.