Arginase-1 (ARG1) is also known as Liver-type arginase, Type I arginase, which belongs to the arginase family. Arginase-1 / ARG1 is a manganese-containing enzyme. The reaction catalyzed by this enzyme is: arginine + H2O ¡ú ornithine + urea. It is the final enzyme of the urea cycle. Defects in Arginase-1 / ARG1 are the cause of argininemia (ARGIN).