Human Arginase Activity Assay
Arginase, an enzyme that hydrolyzes arginine to ornithine and urea in the urea cycle, is expressed primarily in the liver and to some extend in the erythrocytes (type I), as well as in many extrahepatic tissues, such as brain, spinal cord, kidney, small intestine, and mammary gland (type II). Human arginase I, circulating as a homotrimer in blood, is used clinically as a liver-specific marker, which may reflect liver injury status for monitoring conditions of patients with liver disorders or pre- and postoperative conditions of partial hepatectomy patients, and may also play an important role in autoimmune inflammation.
Arginase can be measured as protein concentration by ELISA or as enzyme activity
This radio-enzymatic assay measures the arginase activity in fresh or frozen serum, plasma, red blood cell lysates, or tissue culture cell lysates. The activity is reported as µmoles of arginine broken down per ml of sample per hour (µmole/ml/hr). 1U of arginase is defined as the amount that converts 1 µmol of arginine to ornithine and urea per minute at 37°C. As RBC contain arginase, any hemolysis during blood collection or processing needs to be prevented for accurate measurements in plasma or serum.