A colorimetric microplate assay method for high-throughput analysis of arginase activity in vitro.

Several analytical methods have been developed for the determination of arginase (l-arginine amidinohydrolase) activity in physiological samples. These methods are limited by the considerable effort and time required to obtain reliable and reproducible measurements. Here we describe a simple high-throughput colorimetric assay for the determination of arginase activity based on the ornithine-ninhydrin reaction. This method is an improvement over the original single cuvette assay developed by Chinard in that no boiling step is required. The turnaround time has been reduced, with improved precision and reproducibility. The method was extended to the determination of arginase activity in human leukemic (K562) cells and sickle erythrocytes. We believe that the method will find applications for routine analysis as well as for characterizing the action of novel and potent inhibitors on arginase activity.