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Title: Incorporating a guanidine-modified cytosine base into triplex-forming PNAs for the recognition of a C-G pyrimidine–purine inversion site of an RNA duplex
Authors: Toh, Desiree-Faye Kaixin
Devi, Gitali
Patil, Kiran M.
Qu, Qiuyu
Maraswami, Manikantha
Xiao, Yunyun
Loh, Teck Peng
Zhao, Yanli
Chen, Gang
Keywords: Cytosine
Issue Date: 2016
Source: Toh, D.-F. K., Devi, G., Patil, K. M., Qu, Q., Maraswami, M., Xiao, Y., et al. (2016). Incorporating a guanidine-modified cytosine base into triplex-forming PNAs for the recognition of a C-G pyrimidine–purine inversion site of an RNA duplex. Nucleic Acids Research, 44 (19), 9071-9082.
Series/Report no.: Nucleic Acids Research
Abstract: RNA duplex regions are often involved in tertiary interactions and protein binding and thus there is great potential in developing ligands that sequence-specifically bind to RNA duplexes. We have developed a convenient synthesis method for a modified peptide nucleic acid (PNA) monomer with a guanidine-modified 5-methyl cytosine base. We demonstrated by gel electrophoresis, fluorescence and thermal melting experiments that short PNAs incorporating the modified residue show high binding affinity and sequence specificity in the recognition of an RNA duplex containing an internal inverted Watson-Crick C-G base pair. Remarkably, the relatively short PNAs show no appreciable binding to DNA duplexes or single-stranded RNAs. The attached guanidine group stabilizes the base triple through hydrogen bonding with the G base in a C-G pair. Selective binding towards an RNA duplex over a single-stranded RNA can be rationalized by the fact that alkylation of the amine of a 5-methyl C base blocks the Watson–Crick edge. PNAs incorporating multiple guanidine-modified cytosine residues are able to enter HeLa cells without any transfection agent.
ISSN: 0305-1048
DOI: 10.1093/nar/gkw778
Schools: School of Physical and Mathematical Sciences 
Rights: © 2016 The Author(s). Published by Oxford University Press on behalf of Nucleic Acids Research. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:SPMS Journal Articles

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