DNA-psoralen: single-molecule experiments and first principles calculations

TL;DR

This study combines single-molecule experiments and first principles calculations to investigate how psoralen affects DNA's physical properties, revealing critical concentration effects and providing atomistic insights into DNA-psoralen interactions.

Contribution

It presents the first combined experimental and computational analysis of DNA-psoralen complexes, elucidating their mechanical and structural behavior at different concentrations.

Findings

Persistence length increases then decreases at critical concentration

Contour length remains relatively constant

Atomistic calculations support experimental observations

Abstract

The authors measure the persistence and contour lengths of DNA-psoralen complexes, as a function of psoralen concentration, for intercalated and crosslinked complexes. In both cases, the persistence length monotonically increases until a certain critical concentration is reached, above which it abruptly decreases and remains approximately constant. The contour length of the complexes exhibits no such discontinuous behavior. By fitting the relative increase of the contour length to the neighbor exclusion model, we obtain the exclusion number and the intrinsic intercalating constant of the psoralen-DNA interaction. Ab initio calculations are employed in order to provide an atomistic picture of these experimental findings.