The cis‐state of an azobenzene photoswitch is stabilized through specific interactions with a protein surface

Abstract

The photocontrol of protein function like enzyme activity has been the subject of many investigations to enable reversible and spatiotemporally defined cascading biochemical reactions without the need for separation in miniaturized and parallelized assay setups for academic and industrial applications. A photoswitchable amidohydrolase variant from Bordetella/Alcaligenes with the longest reported half-life (approximately 30 h) for the cis-state of the attached azobenzene group was chosen as a model system to dissect the underlying mechanism and molecular interactions that caused the enormous deceleration of the thermal cis-to-trans relaxation of the azobenzene photoswitch. A systematic site-directed mutagenesis study on the basis of molecular dynamics simulation data was employed to investigate enzyme and thermal cis-to-trans relaxation kinetics in dependence on selected amino acid substitution, which revealed a prominent histidine and a hydrophobic cluster as molecular determinants for the stabilization of the cis-isomer of the attached azobenzene moiety on the protein surface. The nature of the involved interactions consists of polar, hydrophobic, and possibly aromatic Π-Π contributions. The elucidated principles behind the stabilization of the cis-state of azobenzene derivatives on a protein surface can be exploited to design improved biologically inspired photoswitches. Moreover, the findings open the door to highly long-lived cis-states of azobenzene groups yielding improved bistable photoswitches that can be controlled by single light-pulses rather than continuous irradiation with UV light that causes potential photodamage to the employed biomolecules.

Engineered control of enzyme structural dynamics and function

“…Azobenzene‐maleimide probes were attached through a single Cys substitution on an important loop in bacterial histone deacetylase amidohydrolase (HDAH) to create a light‐switchable enzyme . The modified HDAH enzyme was more active when the azobenzene photoswitch was in the trans ‐ compared to the cis ‐configuration, potentially because in the cis ‐configuration the moiety interacts with the enzyme surface …”

“…154 The modified HDAH enzyme was more active when the azobenzene photoswitch was in the trans-compared to the cis-configuration, potentially because in the cis-configuration the moiety interacts with the enzyme surface. 155 Surface-exposed Cys residues may in general serve as attachment points for novel, allosteric modulators. Recently, Wu and coworkers have created the "cysteinome"-a comprehensive database of proteins with targetable cysteines along with any known covalent inhibitors.…”

Direct Color Observation of Light‐Driven Molecular Conformation‐Induced Stress

“…[46,47] This fact has been associated to many different factors, including environmental conditions, specific chemical interactions, and molecules density. [37,[47][48][49] Relaxation times under air occurring in a time scale of more than 1 day were observed in azobenzenealkanethiols self-assembled monolayers, in comparison with the order of minutes observed under vacuum. [48] Furthermore, excessive molecules density can sterically hinder the switching.…”

Synthesis, molecular structure, FT-IR, FT-Raman and XRD spectroscopic investigations of (E)-1-(5-((4-bromophenyl)diazenyl)-2- hydroxyphenyl)ethanone: A comparative DFT study

“…Moreover, azobenzene derivatives upon photo-irradition with UV light show isomerisation over reversal between their trans and cis forms [12][13][14][15][16][17][18] and resistance to thermal decomposition [19][20][21]. This fact enables azobenzenes to control the motion of different moities in molecules containing them [22] and so to use as a photoswitch in smart surfaces [23] and biochemical systems [24]. For instance, in biological systems, photo-induced dynamics of azo compounds changes enzyme activity and function of proteins [24,25].…”

“…This fact enables azobenzenes to control the motion of different moities in molecules containing them [22] and so to use as a photoswitch in smart surfaces [23] and biochemical systems [24]. For instance, in biological systems, photo-induced dynamics of azo compounds changes enzyme activity and function of proteins [24,25]. Nowadays, azobenzene based-polymers have given promise in using as storage devices of optical data as consequence of significant non-linear optics feature [26][27][28][29].…”