SYNTHETIC REPEATING SEQUENCE DNAS CONTAINING PHOSPHOROTHIOATES - NUCLEASE SENSITIVITY AND TRIPLEX FORMATION
SYNTHETIC REPEATING SEQUENCE DNAS CONTAINING PHOSPHOROTHIOATES - NUCLEASE SENSITIVITY AND TRIPLEX FORMATION
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DOI：
10.1093/nar/17.4.1549
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发表时间：
1989-02-25
影响因子：
14.9
通讯作者：
LEE, JS
中科院分区：
文献类型：
--
作者：
LATIMER, LJP;HAMPEL, K;LEE, JS
用DNA聚合酶I从合适的dXTP中制备了20多个含有硫代硫化物的重复序列DNA，修饰后的DNA的TMS均低于母体聚合物。硫代基团5‘到嘧啶的降幅大于5’到嘌呤的降幅，例如聚(Da).cntdot。Poly(DT)=50度；Poly(DSA).cntdo.Poly(Dt)=44度；Poly(Da)·cntdo.Poly(DST)=33°；和Poly(DSA)·cntdo.Poly(DST)=26度。硫代基团的存在对三链的形成有很大的影响；聚[d(TC)].Poly[d(SGSA)]在pH=8时自发错位为三链，而Poly[d(STSC)].cntpoint则形成三链。Poly[d(GA)]被抑制。出人意料的Poly(DSG).cntdot。Poly(DC)的Tm最初随着离子强度的增加而减小。对胰腺DNase I消化的抵抗力与硫代磷酸含量无关。Poly[d(AST)]，Poly[DTSC].Poly[d(SGA)]和Poly[d(Stg)].Poly[d(Sca)]是抗性的，而Poly[d(Sat)]和Poly[d(STsTG)].cntdot是抗性的。聚[d(CsAsA)]被迅速降解。因此，硫代磷酸基引起小的构象变化，并可能揭示新的构象多态家族。
More than twenty repeating sequence DNAs containing phosphorothioates were prepared from the appropriate dXTPs with DNA polymerase I. The Tms of the modified DNAs were all lower than the parent polymers. A phosphorothioate group 5'' to a pyrimidine gave rise to a larger decrease than 5'' to a purine, e.g., poly(dA) .cntdot. poly(dT) = 50.degree.; poly(dsA) .cntdot. poly(dT) = 44.degree.; poly(dA) .cntdot. poly(dsT) = 33.degree.; and poly(dsA) .cntdot. poly(dsT) = 26.degree.. The presence of phosphorothioate groups had a dramatic effect on triplex formation; poly[d(TC)] .cntdot. poly[d(sGsA)] spontaneously dismutates to a triplex at pH 8 whereas triplex formation in poly[d(sTsC)] .cntdot. poly[d(GA)] was inhibited. Surprisingly poly(dsG) .cntdot. poly(dC) had a Tm which initially decreased with increasing ionic strength. Resistance to digestion with pancreatic DNAse I did not correlate with phosphorothioate content. Poly[d(AsT)], poly[dTsC)] .cntdot. poly [d(sGA)] and poly[d(sTG)] .cntdot. poly[d(sCA)] were resistant whereas poly[d(sAT)] and poly[d(sTsTG)] .cntdot. poly[d(CsAsA)] were rapidly degraded. Thus phosphorothioate groups cause small conformational changes and may reveal new families of conformational polymorphisms.