Trends in Biotechnology
Research FocusPNA and LNA throw light on DNA
Section snippets
Singly labeled conformationally restricted fluorogenic probes
It is evident that singly labeled probes are more practical than dual-labeled probes because minimal DNA modification eliminates common problems caused by tagging two DNA sites, including low yield, high cost and singly labeled impurities. In the recent study from Caliper Technologies Corp. (Mt. View, CA, USA) the backbone-modified LNA (locked nucleic acid)-based probes were 5′ end-labeled with either rhodamine or hexachlorofluorescein and their hybridization to target DNAs was followed by
A change of backbone plus use of light-harvesting ‘helpers’
Besides LNA, peptide nucleic acid (PNA) is another promising synthetic imitator of natural nucleic acids 13, 14. However, unlike LNA comprising a slightly modified RNA backbone, the PNA backbone is radically different, although it is structurally homomorphous to nucleic acid forms (Fig. 2). Similar to LNA, PNA exhibits excellent biochemical stability along with high binding affinity and high recognition specificity. In addition, owing to an electrically neutral pseudopeptide backbone, PNA
Combing stemless DNA beacons with PNA ‘openers’
One more twist in the story of PNA-assisted fluorescent DNA detection, now with probing the DNA methylation status by stemless DNA beacons, came very recently from the study of a Japanese group at Kyoto University and Japan Science & Technology Corporation [21]. Site-specific DNA methylation is involved in the regulation of gene expression and gene silencing, and is believed to cause a significant number of transition mutations responsible for human genetic diseases and cancer. Therefore,
Concluding remarks
Notwithstanding great progress that microarrays brought to the area of heterogeneous, solution-to-surface nucleic acid hybridization assays, the homogeneous approaches have certain important advantages. At present, a variety of fluorogenic DNA or RNA-based probes was developed that allow the real-time sequence-specific optical DNA detection in solution. As shown here, the recent advent in the field of LNA and PNA oligomers significantly enlarges the potential of profluorescent probes and gives
Acknowledgements
The author is supported, in part, by the Boston University Provost's Innovation Fund (PIF award) and the National Institutes of Health (GM59173).
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