Oligonucleotide−Oligospermine Conjugates (Zip Nucleic Acids): A Convenient Means of Finely Tuning Hybridization Temperatures

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• 作者：Ré ; gis Noir ; Mitsuharu Kotera ; Bé ; né ; dicte Pons ; Jean-Serge Remy ; Jean-Paul Behr
• 刊名：Journal of the American Chemical Society
• 出版年：2008
• 出版时间：October 8, 2008
• 年：2008
• 卷：130
• 期：40
• 页码：13500-13505
• 全文大小：334K
• 年卷期：v.130,no.40(October 8, 2008)
• ISSN：1520-5126

文摘

Synthesis of oligonucleotide probes and control of their hybridization temperature are key aspects of polymerase chain reaction (PCR)-based detection of genetic sequences. A straightforward means to approach the last goal is to decrease the repulsion between the polyanionic probe and target strands. To this end, we have developed a versatile automated synthesis of oligonucleotide−oligospermine derivatives that gave fast access to a large variety of compounds. Plots of their hybridization temperatures T_m vs overall charge provided a measure of the impact of interstrand phosphate repulsion (and of spermine-mediated attraction) on the main driving force of duplex formation, i.e., base pairing. It showed that stabilization brought about by excess cationic charges can be of larger absolute magnitude than interstrand repulsion, even in high salt media. Base sequence and conjugation site (3′ or 5′) hardly influenced the effect of spermine on T_m. In typical PCR probe conditions, the T_m increased linearly with the number of grafted spermines (e.g., 6.2 °C per spermine for a decanucleotide probe). The large data set of T_m vs number of spermines and oligonucleotide length allowed us to empirically derive a simple mathematical relation that is accurately predicting the T_m of any oligonucleotide−oligospermine derivative. Zip nucleic acids (ZNA) are thus providing an interesting alternative to locked nucleic acids (LNA) or minor groove binders (MGB) for raising the stability of 8−12-mer oligonucleotides up to ca. 70 °C, the level required for quantitative PCR experiments.