Arginase is a key element in the urea cycle, catalyzing the conversion of L-arginine to urea and L-ornithine, thereby promoting collagen synthesis and cell proliferation. Arginine metabolism is a critical regulatory factor in innate and adaptive immune responses and is involved in the antibacterial effects of polymorphonuclear leukocytes (PMNs). During PMN apoptosis, arginine is depleted in the microenvironment, leading to the inhibition of T-cell and natural killer cell proliferation and cytokine secretion. Arginase 1 (ARG1) is a member of the arginase family and has a molecular weight of 35-40 kDa. It is expressed in various cell types, including erythrocytes, hepatocytes, neutrophils, smooth muscle cells, and macrophages. Human ARG1 consists of 322 amino acids (aa), with the enzyme domain located from aa 9 to 309 and containing two Mn atoms. The monomer of ARG1 exhibits moderate activity, but as a homotrimer of 105 kDa, it displays high activity.