Evidence for blocked 5'-termini in human adenovirus DNA.
Evidence for blocked 5'-termini in human adenovirus DNA.
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人类腺病毒 DNA 5 末端被封闭的证据。
DOI：
10.1016/0042-6822(77)90310-5
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发表时间：
1977
期刊：
影响因子：
3.7
通讯作者：
E. Carusi
中科院分区：
文献类型：
--
作者：
E. Carusi
使用DNA中5 ' -和3 ' -末端的特异性酶，研究了六种人类腺病毒血清型的DNA分子，代表了三种致癌类别。用木瓜蛋白酶、十二烷基硫酸钠和苯酚顺序处理纯化的DNA得到的结果表明，所有这些DNA的大部分5 '端被阻断。根据DNA来源的不同，即使经过广泛的碱性磷酸酶处理，50 - 80%的5 '端仍不能被多核苷酸激酶接触到。具有无法磷酸化的5 ‘端的DNA分子也对λ外切酶具有抗性，λ外切酶从5 ’端开始水解DNA。在高温磷酸酶处理或变性单链DNA的磷酸酶处理后，这些5 '端仍然无法磷酸化。然而，在氢氧化钠对腺病毒2 DNA进行长期处理后，大约40%被阻断的5 '端可以被磷酸酶和多核苷酸激酶接近。这些发现表明，一个强键取代基而不是一个特殊的DNA构象解释了不可接近的5 '端。5 ‘阻断基团不影响3 ’末端的反应性，因为所有分子都受到从3 '末端开始水解DNA的核酸外切酶III的攻击。最后，在所有检测的腺病毒血清型中，在可标记的DNA分子的5 '端发现的核苷酸主要是脱氧胞苷酸。
DNA molecules from six human adenovirus serotypes, representative of three oncogenic classes, were investigated using enzymes specific for 5′-, and for 3′-termini in DNA. Results obtained with DNA purified by sequential treatment with papain, sodium dodecyl sulfate, and phenol show that the majority of the 5′-termini of all these DNAs is blocked. Depending upon the source of DNA, from 50 to 80% of the 5′-termini are inaccessible to polynucleotide kinase even after extensive alkaline phosphatase treatment. The DNA molecules with 5′-termini inaccessible to phosphorylation are also resistant to λ exonuclease which hydrolyzes DNA starting from 5′-ends. These 5′-termini remain inaccessible to phosphorylation after high temperature phosphatase treatment, or after phosphatase treatment of denatured, single-stranded DNA. However, about 40% of the blocked 5′-termini of adenovirus 2 DNA becomes accessible to phosphatase and polynucleotide kinase after prolonged treatment of the DNA with sodium hydroxide. These findings suggest that a strongly bonded substituent rather than a peculiar DNA conformation accounts for the inaccessible 5′-termini. The 5′-blocking group does not affect the reactivity of the 3′-termini since all of the molecules are attacked by exonuclease III, which hydrolyzes DNA starting from 3′-ends. Finally, in all of the adenovirus serotypes examined, the nucleotide found at the 5′-termini of DNA molecules accessible to labeling is predominantly deoxycytidylate.