A liver enzyme that performs the final step of the urea cycle, splitting arginine into urea and ornithine so the body can excrete the nitrogen left over from protein metabolism. Without this reaction, ammonia from amino acid breakdown would accumulate to toxic levels, which is why defects in arginase or other urea cycle enzymes cause devastating metabolic disease. The enzyme requires manganese as a cofactor, linking trace mineral nutrition to nitrogen disposal. Beyond the liver, arginase appears in immune cells and other tissues where it competitions with nitric oxide synthesis, influencing inflammation and blood vessel function. In food science it is mainly a biochemical reference point, illustrating how the protein we eat becomes the urea we excrete through an elegant, tightly regulated cycle.