Deoxyuridine triphosphate nucleotidohydrolase: distribution of the enzyme in various rat tissues

The distribution of deoxyuridine triphosphate nucleotidohydrolase (dUTPase) [EC 3.6.1.23] in the cytosol of various rat tissues was investigated by measuring the enzyme activity and by immunochemical analyses. Among nine rat tissues, thymus, and spleen showed the highest activities of the enzyme per gram of tissue, while intestine, stomach, lung and liver showed very low levels. Rabbit antibodies directed against purified dUTPase of anemic rat spleen showed reactivity with partially purified dUTPases from other rat tissues such as thymus, testis, or regenerating liver. Immunotitration and immunoblot experiments also indicated that the dUTPases in various rat tissues had very similar antigenicity and apparently the same subunit molecular size (Mr = 19,500), suggesting that the enzyme lacks organ-specificity. Immunoblot analysis of dUTPase protein with crude extracts from various rat tissues showed a similar distribution to that of the enzyme activity. No immuno-reactive band corresponding to the dUTPase was detected in intestine, although intestinal mucosa has been recognized as an actively proliferating tissue.