Related Experiment Video
Updated: Mar 29, 2026

CD Spectroscopy to Study DNA-Protein Interactions
Published on: February 10, 2022
Depletion interactions and modulation of DNA-intercalators binding: Opposite behavior of the "neutral" polymer
F A P Crisafuli1, L H M da Silva2, G M D Ferreira2
1Departamento de Física, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil.
Abstract:
In this work we have investigated the role of high molecular weight poly(ethylene-glycol) 8000 (PEG 8000) in modulating the interactions of the DNA molecule with two hydrophobic compounds: Ethidium Bromide (EtBr) and GelRed (GR). Both compounds are DNA intercalators and are used here to mimic the behavior of more complex DNA ligands such as chemotherapeutic drugs and proteins whose domains intercalate DNA. By means of single-molecule stretching experiments, we have been able to show that PEG 8000 strongly shifts the binding equilibrium between the intercalators and the DNA even at very low concentrations (1% in mass). Additionally, microcalorimetry experiments were performed to estimate the strength of the interaction between PEG and the DNA ligands. Our results suggest that PEG, depending on the system under study, may act as an "inert polymer" with no enthalpic contribution in some processes but, on the other hand, it may as well be an active (non-neutral) osmolyte in the context of modulating the activity of the reactants and products involved in DNA-ligand interactions.
Related Concept Videos
Inhibitors of Bacterial DNA Synthesis
Drugs that Destabilize Microtubules
DNA Damage can Stall the Cell Cycle
DNA Damage Can Stall the Cell Cycle
Drugs that Stabilize Microtubules
DNA Topoisomerases
Types and Mechanism of action
Topoisomerases are divided into two main types. ...

