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National Chung Hsing University Institutional Repository - NCHUIR > 生命科學院 > 生物化學研究所 > 依資料類型分類 > 期刊論文 >  Binding of actinomycin D to single-stranded DNA of sequence motifs d(TGTCT(n)G) and d(TGT(n)GTCT)

Please use this identifier to cite or link to this item: http://nchuir.lib.nchu.edu.tw/handle/309270000/130839

標題: Binding of actinomycin D to single-stranded DNA of sequence motifs d(TGTCT(n)G) and d(TGT(n)GTCT)
作者: Chen, F.M.;Sha, F.;Chin, K.H.;Chou, S.H.
關鍵字: tetranucleotide sequences;gpc sites;model;drug;specificities;complex;xgcy
日期: 2003
Issue Date: 2012-12-07 16:08:59 (UTC+8)
關連: Biophysical Journal, Volume 84, Issue 1, Page(s) 432-439.
摘要: Our recent binding studies with oligomers derived from base replacements on d(CGTCGTCG) had led to the finding that actinomycin D (ACTD) binds strongly to d(TGTCATTG) of apparent single-stranded conformation without GpG sequence. A fold-back binding model was speculated in which the planar phenoxazone inserts at the GTC site with a loop-out T base whereas the G base at the T-terminus folds back to form a basepair with the internal C and stacks on the opposite face of the chromophore. To provide a more concrete support for such a model, ACTID equilibrium binding studies were carried, out and the results are reported herein on oligomers of sequence motifs d(TGTCT(n)G) and d(TGT(n)GTC). These oligomers are not expected to form dimeric duplexes and contain no canonical GpC sequences. It was found that ACTD binds strongly to d(TGTCTTTTG), d(TGTTTTGTC), and d(TGTTTTTGTC), all exhibiting 1:1 drug/strand binding stoichiometry. The fold-back binding model with displaced T base is further supported by the finding that appending TC and TCA at the T-terminus of d(TGTCTTTTG) results in oligomers that exhibit enhanced ACTD affinities, consequence of the added basepairing to facilitate the hairpin formation of d(TGTCTTTTGTG) and d(TGTCTTTTGTCA) in stabilizing the GTC/GTC binding site for juxtaposing the two G bases for easy stacking on both faces of the phenoxazone chromophore. Further support comes from the observation. of considerable reduction in ACTD affinity when GTC is replaced by GTTC in an oligomer, in line with the reasoning that displacing two T bases to form a bulge for ACTD binding is more difficult than displacing a single base. Based on the elucidated binding principle of phenoxazone ring requiring its opposite faces to be stacked by the 3'-sides of two G bases for tight ACTD binding, several oligonucleotide sequences have been designed and found to bind well.
Relation: Biophysical Journal
Appears in Collections:[依資料類型分類] 期刊論文
[依教師分類] 周三和

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