Title

Synthetic, Structural, and RNA Binding Studies on 2-Aminopyridine-Modified Triplex-Forming Peptide Nucleic Acids

Document Type

Article

Publication Title

Chemistry - A European Journal

Publication Date

3-21-2019

Abstract

The development of new RNA-binding ligands is attracting increasing interest in fundamental science and the pharmaceutical industry. The goal of this study was to improve the RNA binding properties of triplex-forming peptide nucleic acids (PNAs) by further increasing the pK a of 2-aminopyridine (M). Protonation of M was the key for enabling triplex formation at physiological pH in earlier studies. Substitution on M by an electron-donating 4-methoxy substituent resulted in slight destabilization of the PNA–dsRNA triplex, contrary to the expected stabilization due to more favorable protonation. To explain this unexpected result, the first NMR structural studies were performed on an M-modified PNA–dsRNA triplex which, combined with computational modeling identified unfavorable steric and electrostatic repulsion between the 4-methoxy group of M and the oxygen of the carbonyl group connecting the adjacent nucleobase to PNA backbone. The structural studies also provided insights into hydrogen-bonding interactions that might be responsible for the high affinity and unusual RNA-binding preference of PNAs.

Volume

25

Issue

17

First Page

4367

Last Page

4372

DOI

10.1002/chem.201806293

ISSN

09476539

E-ISSN

15213765

PubMed ID

30746843

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