Catalyzes the hydrolysis of the amide bond in N-(4-oxoglutarate)-L-cysteinylglycine (deaminated glutathione), a metabolite repair reaction to dispose of the harmful deaminated glutathione. Possesses amidase activity toward deaminated ophthalmate in vitro (PubMed:28373563). Plays a role in cell growth and apoptosis: loss of expression promotes cell growth, resistance to DNA damage stress and increased incidence to NMBA-induced tumors. Has tumor suppressor properties that enhances the apoptotic responsiveness in cancer cells; this effect is additive to the tumor suppressor activity of FHIT. It is also a negative regulator of primary T-cells. H2O + N-(4-oxoglutaryl)-L-cysteinylglycine = 2-oxoglutarate + L-cysteinylglycine H2O + N-(4-carboxy-4-oxobutanoyl)-L-ethylglycylglycine = 2-oxoglutarate + N-(2-aminobutanoyl)glycine kcat is 1.6 sec(-1) with N-(4-oxoglutarate)-L-cysteinylglycine as substrate. Expressed in most tissues with higher expression in adult liver and kidney as well as in fetal adrenal gland and skeletal muscle. Mice are normal at birth as well as during growth. Mammary glands exhibit an increase in ductal and alveolar structures as well as more cyclin-D1 positive cells in mid-pregnancy. In the basal layer of epidermis, the number of cyclin-D1 positive cells is also higher. No lymphoid malignancy is observed. Kidney cells lacking Nit1 exhibit round and compact shapes, loss of lobular structure, higher cell density with increased S and G2/M cell populations. Cyclin D1 expression is increased, whereas differences in the other cell cycle-associated proteins appeared minimal. T-cells lacking NIT-1 display enhanced proliferation, elevated activation marker expression, accelerated cell cycle progression and aberrant expression of some cell cycle proteins. According to Rosetta Stone theory, the existence of a fusion protein in one genome predicts that the separate polypeptides expressed in other organisms function in the same cellular or biochemical pathway. In Drosophila melanogaster and Caenorhabditis elegans, NitFhit is a fusion protein composed of a C-terminal Fhit domain and a domain related to plant and bacterial nitrilase. Belongs to the carbon-nitrogen hydrolase superfamily. NIT1/NIT2 family.