Lxxii. Properties of Choline Esterase in Human Serum

THE importance of the physiologically active substance acetylcholine makes it highly desirable that the properties of the enzyme which specifically hydrolyses choline esters be established. Summaries of the past work on this enzyme have recently appeared [Ammon, 1935; Gaddum, 1935; Oppenheimer, 1935]. It is remarkable that although choline esterase has been studied in relation to its partial purification, distribution within the organism, variations in different species, inhibition by compounds of pharmacological interest and in connexion with normal and abnormal physiological functions, some of its most fundamental properties have not yet been adequately investigated. In the present study the activity-pH relationship has been definitely established, and the affinity of the enzyme for acetylcholine has been measured.