Related Experiment Video
Updated: Aug 2, 2025

Synthesis of Wavelength-shifting DNA Hybridization Probes by Using Photostable Cyanine Dyes
Published on: July 6, 2016
Programmable DNA Interstrand Crosslinking by Alkene-Alkyne [2 + 2] Photocycloaddition
Hermann Neitz1, Irene Bessi1, Jochen Kuper2
1Institute of Organic Chemistry, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Abstract:
Covalent crosslinking of DNA strands provides a useful tool for medical, biochemical, and DNA nanotechnology applications. Here we present a light-induced interstrand DNA crosslinking reaction using the modified nucleoside 5-phenylethynyl-2'-deoxyuridine (PhedU). The crosslinking ability of PhedU was programmed by base pairing and by metal ion interaction at the Watson-Crick base pairing site. Rotation to intrahelical positions was favored by hydrophobic stacking and enabled an unexpected photochemical alkene-alkyne [2 + 2] cycloaddition within the DNA duplex, resulting in efficient formation of a PhedU dimer after short irradiation times of a few seconds. A PhedU-dimer-containing DNA was shown to efficiently bind a helicase complex, but the covalent crosslink completely prevented DNA unwinding, suggesting possible applications in biochemistry or structural biology.
Related Concept Videos
Cycloaddition Reactions: Overview
Cycloaddition Reactions: MO Requirements for Thermal Activation
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Electrophilic 1,2- and 1,4-Addition of X2 to 1,3-Butadiene
Homologous Recombination

