METABOLISM OF DITP IN HELA-CELL EXTRACTS, INCORPORATION INTO DNA BY ISOLATED-NUCLEI AND RELEASE OF HYPOXANTHINE FROM DNA BY A HYPOXANTHINE-DNA GLYCOSYLASE ACTIVITY
METABOLISM OF DITP IN HELA-CELL EXTRACTS, INCORPORATION INTO DNA BY ISOLATED-NUCLEI AND RELEASE OF HYPOXANTHINE FROM DNA BY A HYPOXANTHINE-DNA GLYCOSYLASE ACTIVITY
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DOI：
10.1093/nar/10.12.3693
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发表时间：
1982-01-01
影响因子：
14.9
通讯作者：
KROKAN, H
中科院分区：
文献类型：
--
作者：
MYRNES, B;GUDDAL, PH;KROKAN, H
dITP可以通过缓慢的非酶水解由dATP产生。虽然[3 H]dITP被HeLa细胞核提取物迅速降解为[3 H]脱氧肌苷，但在生理浓度的ATP存在下，没有观察到[3 H]dITP的净降解，显然是因为提取物含有脱氧核苷二磷酸激酶活性，可以从[3 H]dIDP再生[3 H]dITP。分离的HeLa细胞核以及部分纯化的DNA聚合酶a以[~ 3 H] dGTP掺入率的50-60%掺入DNA。未观察到掺入的放射性快速释放。然而，含有dIMP残基的新生DNA的分子量在EDTA的存在下长时间孵育后略有下降，这表明修复过程在含有dIMP的染色质中启动。此外，在EDTA存在下与核提取物孵育后，检测到游离[3 H]次黄嘌呤从含[3 H] dIMP的DNA中释放，表明HeLa细胞核中存在次黄嘌呤-DNA糖基化酶活性。
dITP may be generated from dATP by a slow, nonenzymatic hydrolysis. While [3H]dITP was degraded rapidly to [3H]deoxyinos1ne by HeLa cell nuclear extracts, no net degradation of [3H]dITP was observed in the presence of physiological concentrations of ATP, apparently because the extract contained deoxynucleoside diphosphate kinase activity that regenerated [3H]dITP from [3H]dIDP. Isolated HeLa cell nuclei, as well as partially purified DNA poly-merase a, incorporated [3H]dITP into DNA at 50–60% of the rate of [3H]dGTP incorporation. No rapid release of the Incorporated radioactivity was observed. The molecular weight of nascent DNA containing dIMP residues, however, decreased slightly after prolonged incubation in the presence of EDTA, suggesting that a repair process is initiated in dIMP-containing chromatin. Furthermore, release of free [3H]hypoxanthine from [3H]dIMP-contain1ng DNA was detected after incubation with nuclear extracts in the presence of EDTA, suggesting the presence of hypoxanthine-DNA glycosylase activity in HeLa cell nuclei.