Nucleic acid binding and other biomedical properties of artificial oligolysines

Abstract

In the present study, we report the interaction of an artificial oligolysine (referred to as AOL) realized in our laboratory with targets of biomedical importance. These included polyinosinic acid (poly rI) and its complex with polycytidylic acid (poly I:C), RNAs with well-known interferon-inducing ability, and double-stranded (ds) DNA. The ability of the peptide to bind both single-stranded poly rI and ds poly I:C RNAs emerged from our circular dichroism (CD) and ultraviolet (UV) studies. In addition, we found that AOL forms complexes with dsDNA, as shown by spectroscopic binding assays and UV thermal denaturation experiments. These findings are encouraging for the possible use of AOL in biomedicine for nucleic acid targeting and oligonucleotide condensation, with the latter being a key step preceding their clinical application. Moreover, we tested the ability of AOL to bind to proteins, using serum albumin as a model protein. We demonstrated the oligolysine–protein binding by CD experiments which suggested that AOL, positively charged under physiological conditions, binds to the protein regions rich in anionic residues. Finally, the morphology characterization of the solid oligolysine, performed by scanning electron microscopy, showed different crystal forms including cubic-shaped crystals confirming the high purity of AOL.

Keywords:

• nucleic acid binding
• polyinosinic acid
• double-stranded nucleic acids
• oligolysine
• circular dichroism

Acknowledgments

We thank Prof Antonio Roviello for his precious suggestions and Regione Campania for the grant received for the research project “Nuovi sistemi nucleopeptidici per applicazioni diagnostiche” under the research program Legge Regionale n. 5 (annualità 2007).

Disclosure

The authors report no conflicts of interest in this work.