Monitoring Chemical and Biological Electron Transfer Reactions with a Fluorogenic Vitamin K Analogue Probe

J Am Chem Soc. 2016 Dec 21;138(50):16388-16397. doi: 10.1021/jacs.6b09735. Epub 2016 Dec 7.

Abstract

We report herein the design, synthesis, and characterization of a two-segment fluorogenic analogue of vitamin K, B-VKQ, prepared by coupling vitamin K3, also known as menadione (a quinone redox center), to a boron-dipyrromethene (BODIPY) fluorophore (a lipophilic reporter segment). Oxidation-reduction reactions, spectroelectrochemical studies, and enzymatic assays conducted in the presence of DT-diaphorase illustrate that the new probe shows reversible redox behavior on par with that of vitamin K, provides a high-sensitivity fluorescence signal, and is compatible with biological conditions, opening the door to monitor remotely (i.e., via imaging) redox processes in real time. In its oxidized form, B-VKQ is non-emissive, while upon reduction to the hydroquinone form, B-VKQH2, BODIPY fluorescence is restored, with emission quantum yield values of ca. 0.54 in toluene. Density functional theory studies validate a photoinduced electron transfer intramolecular switching mechanism, active in the non-emissive quinone form and deactivated upon reduction to the emissive dihydroquinone form. Our results highlight the potential of B-VKQ as a fluorogenic probe to study electron transfer and transport in model systems and biological structures with optimal sensitivity and desirable chemical specificity. Use of such a probe may enable a better understanding of the role that vitamin K plays in biological redox reactions ubiquitous in key cellular processes, and help elucidate the mechanism and pathological significance of these reactions in biological systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Electrochemistry
  • Electron Transport
  • Fluorescent Dyes / chemistry*
  • Fluorescent Dyes / metabolism
  • Models, Molecular
  • NAD(P)H Dehydrogenase (Quinone) / chemistry
  • NAD(P)H Dehydrogenase (Quinone) / metabolism
  • Protein Conformation
  • Vitamin K / chemistry*
  • Vitamin K / metabolism

Substances

  • Fluorescent Dyes
  • Vitamin K
  • NAD(P)H Dehydrogenase (Quinone)

Grants and funding