Binding of Fe(ii)-complex of phenanthroline appended glycoconjugate with DNA, plasmid and an agglutinin protein

Abstract

The phenanthroline appended glycoconjugate (L) and its Fe(II)-complex were synthesized and characterized using analytical and spectral methods. The complexation of Fe²⁺ with L has been shown using absorption and fluorescence spectral studies. ¹H NMR titration of L with Fe²⁺ supports that the phenanthroline moiety acts as the metal binding core. The interaction and binding of the Fe-complex with calf thymus DNA (ct-DNA) were studied using spectral techniques, such as UV-Vis absorption, circular dichroism (CD) and DNA melting temperatures. The corresponding data supported the minor groove binding of ct-DNA by the Fe-complex along with electrostatic interactions. The gel electrophoresis studies carried out using pBR322 plasmid showed a tight binding of the iron complex with the plasmid and this resulted in the condensation of the pBR322 plasmid as revealed by the blob-like structures observed in the atomic force microscopy data. The binding of the Fe-complex by WGA was demonstrated by absorption, fluorescence and CD spectra, and the microstructures were observed via scanning electron microscopy (SEM). Star-like nanostructures observed via SEM support that the octahedral iron complex connects the protein molecules in three dimensions through their carbohydrate terminal moieties. Thus, a new Fe-complex possessing a biocompatible glucosyl moiety interacts and binds to biomolecules, such as DNA and protein, and the resulting species are of importance in biological applications.