Glycosaminoglycan and DNA binding induced intra- and intermolecular exciton coupling of the bis-4-aminoquinoline surfen

TitleGlycosaminoglycan and DNA binding induced intra- and intermolecular exciton coupling of the bis-4-aminoquinoline surfen
Publication TypeJournal Article
Year of Publication2015
AuthorsZsila, F
JournalChirality
Volume27
Issue9
Pagination605-12
Date Published2015 Sep
ISSN1520-636X
Abstract

Despite the diverse biological activities of the glycosaminoglycan (GAG) antagonist surfen, the molecular details of its interaction with biomacromolecules remain poorly understood. Therefore, heparin and DNA binding properties of surfen were studied by circular dichroism (CD) and UV absorption spectroscopy methods. High-affinity (Ka  ~ 10(7)  M(-1)) association of surfen to the chiral heparin chain gives rise to a characteristic biphasic CD pattern due to the conformational twist of the aminoquinoline moieties around the central urea bridge. At higher drug loading, intermolecular stacking of surfen molecules alters the induced CD profile and also provokes strong UV hypochromism. In contrast to the right-handed heparin template, binding of surfen to the left-helicity chondroitin sulfate chains produces inverted CD pattern. Large UV hypochromism as well as polyphasic induced ellipticity bands indicate that surfen intercalates between the base pairs of calf-thymus DNA. Extensive CD spectroscopic changes observed at higher drug binding ratios refer to cooperative binding interactions between the intercalated drug molecules. The inherent conformational flexibility of surfen demonstrated here for the first time is important in its binding to distinct macromolecular targets and should be considered for rational drug design of novel GAG antagonists.

DOI10.1002/chir.22471
Alternate JournalChirality
PubMed ID26096963