Photoregulation of the transcription reaction of T7 RNA polymerase by tethering an azobenzene to the promoter.
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Azo Compounds↗
Biomedical subjects
Hiroyuki Asanuma
Publications and source records attributed to Hiroyuki Asanuma.
Photoregulation of DNA triplex formation by azobenzene.
Formation and dissociation of DNA triplex are reversibly photoregulated by cis <--> trans isomerization of the azobenzene tethered to the third strand. When the azobenzene takes the trans from, a stable triplex is formed. Upon the isomerization of trans-azobenzene to its cis form by UV light irradiation (300 < lambda < 400 nm), however, the modified oligonucleotide is removed from the target duplex. The triplex is re-formed on photoinduced cis --> trans isomerization (lambda > 400 nm). The photoregulating activity significantly depends on the position of azobenzene in the third strand, as well as on the geometric position (meta or para) of its amido substituent. For m-amidoazobenzene, the photoregulation is the most effective when it is tethered to the 5'-end of the third strand. However, p-amidoazobenzene should be introduced into the middle of the strand for effective regulation. In the optimal cases, the change of T(m) of the triplex, caused by the cis <--> trans isomerization of azobenzene, is greater than 30 degrees C. UV-visible and CD spectroscopy, as well as computer modeling studies, clearly demonstrate that the trans-azobenzene intercalates between the base pairs in the target duplex and thus stabilizes the triplex by stacking interactions. On the other hand, nonplanar cis-azobenzene destabilizes the triplex due to its steric hindrance against the adjacent base pairs.
Azo Compounds↗
Spectroscopic anatomy of molecular-imprinting of cyclodextrin. Evidence for preferential formation of ordered cyclodextrin assemblies.
The processes of molecular-imprinting of beta-cyclodextrin (beta-CyD) with cholesterol and stigmasterol (cross-linking agent = diisocyanate) have been analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy. These templates enormously promote the formation of dimers and trimers of beta-CyD, which are only inefficiently formed in their absence. These ordered assemblies are the guest-binding sites, in which two or three beta-CyD molecules cooperate to bind large steroids. Ordered assemblies are also formed when 2,6-di-O-methyl-beta-cyclodextrin is used in place of beta-CyD. Direct spectroscopic evidence for molecular-imprinting effect has been obtained. Molecular imprinting of CyDs is potent for tailor-made preparation of synthetic receptors for nanometer-scaled guests.
Cholesterol↗
Photo-regulation of transcription by RNA polymerase with azobenzene-tethered promoter.
Photo-regulation of transcription reaction by T7-RNA polymerase was investigated by introducing an azobenzene residue into the non-template strand of T7-promoter. It was found that transcription was strongly interfered under dark or visible light irradiation, whereas it efficiently proceeded after UV irradiation. With this photo-responsive promoter, on-off switching of transcription by light irradiation was achieved. This strategy was also effective for the photo-regulation of SP6-RNA polymerase.
Base Sequence↗
Enantioselective Incorporation of Azobenzenes into Oligodeoxyribonucleotide for Effective Photoregulation of Duplex Formation This work was partially supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan (Molecular Synchronization for Design of New Materials System). The support by the Grant from "Research for the Future" Program of the Japan Society for the Promotion of Science (JSPS-RFTF97I00301) is also acknowledged.
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Journal Article↗