Conformational Changes of DNA by Photoirradiation of DNA-Bis(Zn^II-Cyclen)-Azobenzene Complex

Bis(Zn^II-cyclen)-azobenzene derivative, which has two Zn^II-macrocyclic tetraamine complexes connected through azobenzene spacer, has been synthesized as a cross-linking agent for double stranded DNA in aqueous solution. The Zn^II-cyclen derivative selectively binds to A-T base pairs producing complexes between the Zn^II-cyclen moiety and the imide-deprotonated thymine with breaking A-T base pairs. The azobenzene spacer undergoes cis/trans photoisomerization in the complex between the Zn^II-cyclen derivative and the DNA duplex. The conformation of the DNA remarkably changed by photoisomerization of the azobenzene linker, when the Zn^II-cyclen derivative binds to the DNA duplex with an interstrand cross-linking manner.

Keywords:

• Zn^II-cyclen
• Azobenzene
• Photoisomerization
• Conformational change

Acknowledgments

We thank Professor Yoshihisa Inoue, Professor Takehiko Wada, and Dr. Hideo Nishino for technical advice in CD analyses.

This article is dedicated to Professor Eiko Ohtsuka on the occasion of her 70th birthday.

Notes

^aUV-melting curves monitored at 260 nm were measured with increasing temperature from 0 to 80°C at a rate of 0.5°C/min.