5 years ago

Fluorescence Enhancement of Unconstrained GFP Chromophore Analogues Based on the Push–Pull Substituent Effect

Fluorescence Enhancement of Unconstrained GFP Chromophore Analogues Based on the Push–Pull Substituent Effect
Chi-Jui Tsai, Shih-Sheng Sun, Yen-Chin Huang, Jye-Shane Yang, Yuan-Chung Cheng, Meng-Shiue Tsai, Chun-Lin Ou
Unlike the high fluorescence quantum yield of the naturally occurring green fluorescence protein (GFP, Φf ∼ 0.8), the GFP chromophore, a benzylidenedimethylimidazolinone (BDI) dye, is nearly nonfluorescent (Φf < 0.001) in common solutions at room temperature. While many efforts have been devoted into the BDI chromophore engineering for fluorescence recovery, limited success has been achieved for structurally unconstrained GFP chromophore analogues (uGFPc). Herein we report a rational design of uGFPc toward an unprecedentedly high fluorescence quantum efficiency of 0.60 in hexane. This is achieved by a combined ortho-CN and meta-dimethylamino substituent electronic effect that largely suppresses the ZE photoisomerization (the τ torsion) reaction, which is the major nonradiative decay channel of uGFPc. The structural design relied on the assumptions that the τ torsion of the meta-amino-substituted BDI systems leads to a zwitterionic twisted intermediate state (1p*) and that destabilizing the 1p* state by an electron-withdrawing CN substituent at the ortho or para position could slow down the τ torsion. The observed CN position effect conforms to the design concept. The push–pull substitution of BDI also leads to sensitive fluorescence-quenching responses to electron donors such as trimethylamine and to H-bond donors such as methanol.

Publisher URL: http://dx.doi.org/10.1021/acs.joc.7b01260

DOI: 10.1021/acs.joc.7b01260

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.