Development and regional distribution of deoxyuridine 5'-triphosphatase in rabbit brain

The development and regional distribution of deoxyuridine 5'-triphosphatase (dUTPase) in rabbit brain was studied. After partial purification of the dUTPase activity, newborn brain and liver activities fell from Vmax values of 1.0 and 6.9 nmol/mg protein/min, respectively, to adult levels of 0.1 (brain) and less than 0.01 (liver). The dUTPase activity was evenly distributed throughout the entire adult rabbit brain, and there was no difference in the Km of dUTPase in newborn and adult brain (0.1 microM). The low level of dUTPase in adult brain and the lack of activity in adult liver were not due to inhibitors or phenylmethylsulfonyl fluoride-sensitive proteases. dUTPase in brain, as in other tissues, probably inhibits the misincorporation of uracil into DNA.