Light-controlled out-of-equilibrium assembly of cyclodextrins in an enzyme-mediated dynamic system

Abstract

In this doubly dynamic system, we use light to control the outcome of an enzyme-driven process, exploiting a photoswitchable azobenzene template to direct the selective synthesis of different cyclodextrins.

Molecular photoswitches in aqueous environments

“…[156][157][158] They became frequently used photoswitches and can be found in a diverse range of applications due to their small size, reliable photochemical behaviour, and the versatility of methods available to synthesize and functionalize them. [156][157][158][159][160] As a result, (heteroaryl)azobenzenes are quite well understood and were the subject of extensive fundamental studies. Like with the previously described stilbenes, the large geometrical change that azobenzenes undergo upon double bond isomerization significantly alters their chemical and photochemical properties.…”

Dynamic enzymatic synthesis of γ-cyclodextrin using a photoremovable hydrazone template

“…36 We have recently described how the reversible enzymatic synthesis of CDs can be controlled 37,38 by adding photoreversible templates (guests). 39 However, the use of azobenzene as the photoswitchable guest only resulted in the optical control over the ratios of the aand b-CDs, and no appreciable increase in the yield of g-CD was observed. Addressing the synthetic and isolation challenges facing the production of g-CD requires a paradigm shift in approach, which will require the development of new photochromic guests.…”

“…37 Templates that bind to specific CDs can further stabilize these products, leading to both higher CD yields and selective synthesis of CDs. [37][38][39] We began by treating a solution of maltohexaose (G6) (6 mg/mL) in sodium phosphate buffer (50 mM, pH 7.5) with CGTase (0.6 mg/mL) in the presence of either 1-E (10 mM) or 1-Z (10 mM) in the dark. The reaction was monitored using HPLC coupled with an evaporative light scattering detector (ELSD).…”

Unnatural cyclodextrins can be accessed from enzyme-mediated dynamic combinatorial libraries

“…Enzyme-mediated dynamic combinatorial chemistry uses enzymes as catalysts to make dynamic combinatorial libraries (DCLs) of interconverting oligomers. 1–10 Due to the natural origins of the enzymes, the building blocks for these oligomers are natural biomonomers, such as amino acids 1–4 or carbohydrates. 5–10 Such dynamic systems have enabled the development of peptide-based nanomaterials from protease-catalysed systems 2,3 and the exploration of light-controlled dynamic systems of cyclodextrins (CDs), where the relative ratios of α, β and γ-CD can be controlled by an external light source.…”

“…5–10 Such dynamic systems have enabled the development of peptide-based nanomaterials from protease-catalysed systems 2,3 and the exploration of light-controlled dynamic systems of cyclodextrins (CDs), where the relative ratios of α, β and γ-CD can be controlled by an external light source. 9,10…”