Department of Chemical Sciences, Federico II University, Via Cintia 21, 80126 Naples, Italy
b
Istituto di Biostrutture e Bioimmagini IBB - CNR, Via Mezzocannone 16, 80134 Naples, Italy
References: Not available.
Synthesis and nucleic acid binding evaluation of a thyminyl L-diaminobutanoic acid-based nucleopeptide
Herein we present the synthesis of a L-diaminobutanoic acid (DABA) -based nucleopeptide (3), with an oligocationic backbone, realized by solid phase peptide synthesis with thymine-bearing DABA moieties alternating in the sequence with free ones. CD studies evidenced the ability of this oligothymine nucleopeptide, well soluble in aqueous solution, to alter the secondary structure particularly of complementary RNA (poly rA vs poly rU) and inosine-rich RNAs, like poly rI and poly rIC, and showed its preference in binding double vs single-stranded DNAs. Furthermore, ESI mass spectrometry revealed that 3 bound also G-quadruplex (G4) DNAs, with both parallel and antiparallel topologies (adopted in our experimental conditions by c-myc and tel22, respectively). However, it caused detectable changes only in the CD of c-myc (whose parallel G4 structure was also thermally stabilized by ∼3 °C), while leaving unaltered the antiparallel structure of tel22. Interestingly, CD and UV analyses suggested that 3 induced a hybrid mixed parallel/antiparallel G4 DNA structure in a random tel22 DNA obtained under salt-free buffer conditions. Titration of random telomeric DNA with 3 gave a quantitative information on the stoichiometry of the obtained complex (CNH3+/CPO3- =1.5). Overall, the findings of this work suggest that DABA-based nucleopeptides are synthetic nucleic acid analogues potentially useful in antigene and antisense strategies. Nevertheless, the hexathymine DABA-nucleopeptide shows an interesting behaviour as molecular tool itself for its efficacy in provoking G4 induction in disordered G-rich DNA, as well as for the possibility to bind and stabilize c-myc oncogene in a G4 structure.
Synthesis and nucleic acid binding evaluation of a thyminyl L-diaminobutanoic acid-based nucleopeptide