[Comparative characterization of the catalytic properties of blood serum cholinesterase in pigeon and hen].

Significant difference in catalytic properties of partially purified cholinesterases from blood serum of pigeon and hen was shown by photometric method using Ellman's reagent. From eight studied thioesters, pigeon cholinesterase hydrolysed with the highest rate butyrylthiocholine but hen cholinesterase--propionylthiocholine. The enzymatic hydrolysis obeyed Michaelis-Menten equation only at low concentration of substrates up to 0.15-0.5 mM. High concentration of substrates activated hen cholinesterase, but inhibited pigeon cholinesterase.