Direct Measurement of Interhelical DNA Repulsion and Attraction by Quantitative Cross-Linking.

ABSTRACT: To better understand the forces that mediate nucleic acid compaction in biology, we developed the disulfide cross-linking approach xHEED (X-linking of Helices to measure Electrostatic Effects at Distance) to measure the distance-dependent encounter frequency of two DNA helices in solution. Using xHEED, we determined the distance that the electrostatic potential extends from DNA helices, the dependence of this distance on ionic conditions, and the magnitude of repulsion when two helices approach one another. Across all conditions tested, the potential falls to that of the bulk solution within 15 Å of the major groove surface. For separations of ∼30 Å, we measured a repulsion of 1.8 kcal/mol in low monovalent ion concentration (30 mM Na⁺), with higher Na⁺ concentrations

SUBMITTER: Hamilton I 

PROVIDER: S-EPMC8815069 | biostudies-literature | 2022 Feb

REPOSITORIES: biostudies-literature