Tailoring the Structure of Cell Penetrating DNA and RNA Binding Nucleopeptides

Abstract

Synthetic nucleic acid interactors represent an exciting research field due to their biotechnological and potential therapeutic applications. The translation of these molecules into drugs is a long and difficult process that justifies the continuous research of new chemotypes endowed with favorable binding, pharmacokinetic and pharmacodynamic properties. In this scenario, we describe the synthesis of two sets of homo-thymine nucleopeptides, in which nucleobases are inserted in a peptide structure, to investigate the role of the underivatized amino acid residue and the distance of the nucleobase from the peptide backbone on the nucleic acid recognition process. It is worth noting that the CD spectroscopy investigation showed that two of the reported nucleopeptides, consisting of alternation of thymine functionalized L-Orn and L-Dab and L-Arg as underivatized amino acids, were able to efficiently bind DNA and RNA targets and cross both cell and nuclear membranes.

Keywords: cell penetrating peptide synthesis; cell penetrating peptides; nuclear localization sequences; nucleic acid binders; nucleopeptides.

Scheme 1

US-SPPS of nucleopeptides 16–20.

Scheme 2

US-SPPS of nucleopeptides 31–35.

Figure 1

CD spectra of 16–20 (a) and 20, 31–33 (b) nucleopeptides.

Figure 2

CD spectra of 16–20/PolyA hybrids.

Figure 3

CD spectra of 16–20/PolydA hybrids.

Figure 4

CD spectra of 31–33 and 20/PolyA (A) and PolydA (B) hybrids.

Figure 5

CD titration data of polydA and polyA, with 32 and 33, respectively.

Figure 6

Mean fluorescence intensity of the HT29 (a), CCRF-CEM (b) and Jurkat (c) cells containing 34 and 35 by FACS analysis (lower panel) and the representative results of FACS analysis (upper panel). CTR Neg was the fluorescence of untreated cells.