“…For many years, a significant handicap to the study of the properties of arginase has been the lack of a rapid and completely reliable method of assay for this important metabolic enzyme. Methods of determining arginase activity have included measurement of a decrease in arginine concentration (15)(16)(17)(18)(19), an increase in ornithine concentration (20), or an increase in urea concentration and subsequent decomposition of the urea with jack-bean urease followed by manometric (21)(22)(23)(24) determination of the CO2 formed or colorimetric (25)(26)(27) or titrimetric (28) determination of ammonia.…”