Pardo E G, Gutiérrez C
Centro de Investigaciones Biológicas, Madrid, Spain.
Exp Cell Res. 1990 Jan;186(1):90-8. doi: 10.1016/0014-4827(90)90214-u.
Deoxyuridine triphosphate nucleotidohydrolase (dUTPase), a key enzyme in pyrimidine nucleotide metabolism, specifically hydrolyzes deoxyuridine triphosphate (dUTP) to deoxyuridine monophosphate and inorganic pyrophosphate. This enzyme activity has been studied in cellular extracts from Allium cepa root meristem cells with two specific aims: (i) to determine how the properties of the plant enzyme compare with those of dUTPase purified from other sources, and (ii) to analyze the relationship between dUTPase activity and cell proliferation and cell differentiation. Plant dUTPase is highly specific for dUTP, with an apparent Km of 6 microM, is highly sensitive to EDTA and it is probably a metalloenzyme. Our results demonstrate the presence of high levels of dUTPase in both resting and proliferating root meristem cells. The enzyme activity appears to be tightly regulated during the cell cycle. dUTPase activity increases at the G1/S boundary, remains high throughout S phase, and shows almost undetectable levels during G1 and G2. We have also found that dUTPase activity in differentiated cells, located in the mature portion of the root, is barely detectable. Altogether our results indicate that dUTPase activity is modulated by the proliferation rate and that this activity progressively decreases as cells initiate their differentiation program.
脱氧尿苷三磷酸核苷酸水解酶（dUTPase）是嘧啶核苷酸代谢中的一种关键酶，它能特异性地将脱氧尿苷三磷酸（dUTP）水解为脱氧尿苷单磷酸和无机焦磷酸。该酶活性已在洋葱根尖分生组织细胞的细胞提取物中进行了研究，有两个特定目的：（i）确定植物酶的特性与从其他来源纯化的dUTPase的特性相比如何，以及（ii）分析dUTPase活性与细胞增殖和细胞分化之间的关系。植物dUTPase对dUTP具有高度特异性，表观Km为6微摩尔，对EDTA高度敏感，可能是一种金属酶。我们的结果表明，在静止和增殖的根尖分生组织细胞中都存在高水平的dUTPase。该酶活性在细胞周期中似乎受到严格调控。dUTPase活性在G1/S边界处增加，在整个S期保持高水平，而在G1期和G2期几乎检测不到。我们还发现，位于根成熟部分的分化细胞中的dUTPase活性几乎检测不到。总的来说，我们的结果表明dUTPase活性受增殖速率调节，并且随着细胞启动其分化程序，这种活性会逐渐降低。
