Photoswitching the Efficacy of a Small-Molecule Ligand for a Peptidergic GPCR: from Antagonism to Agonism

Article abstract of DOI:10.1002/anie.201804875

For optical control of GPCR function, we set out to develop small-molecule ligands with photoswitchable efficacy in which both configurations bind the target protein but exert distinct pharmacological effects, that is, stimulate or antagonize GPCR activation. Our design was based on a previously identified efficacy hotspot for the peptidergic chemokine receptor CXCR3 and resulted in the synthesis and characterization of five new azobenzene-containing CXCR3 ligands. G protein activation assays and real-time electrophysiology experiments demonstrated photoswitching from antagonism to partial agonism and even to full agonism (compound VUF16216). SAR evaluation suggests that the size and electron-donating properties of the substituents on the inner aromatic ring are important for the efficacy photoswitching. These compounds are the first GPCR azo ligands with a nearly full efficacy photoswitch and may become valuable pharmacological tools for the optical control of peptidergic GPCR signaling.

Full text of DOI:10.1002/anie.201804875

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: Photoswitching the efficacy of a small-molecule ligand for a
peptidergic GPCR: from antagonism to agonism
Authors: Rob Leurs, Xavier Gómez-Santacana, Sabrina M. de Munnik,
Prashanna Vijayachandran, Daniel Da Costa Pereira, Jan
Paul M. Bebelman, Iwan J. P. de Esch, Henry F. Vischer, and
Maikel Wijtmans
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201804875
Angew. Chem. 10.1002/ange.201804875
Link to VoR: http://dx.doi.org/10.1002/anie.201804875
http://dx.doi.org/10.1002/ange.201804875

10.1002/anie.201804875
Angewandte Chemie International Edition
COMMUNICATION
Photoswitching the efficacy of a small-molecule ligand for a
peptidergic GPCR: from antagonism to agonism
Xavier Gómez-Santacana[a], Sabrina M. de Munnik[a], Prashanna Vijayachandran, Daniel Da Costa
Pereira, Jan Paul M. Bebelman, Iwan J. P. de Esch, Henry F. Vischer, Maikel Wijtmans*, Rob Leurs*
Abstract: In order to obtain optical control of GPCR function, we set
out to develop small-molecule ligands with photoswitchable efficacy
in which both configurations bind the target protein but exert distinct
pharmacological effects, i.e., stimulate or antagonize GPCR
activation. Our design was based on a previously identified efficacy
hotspot for the peptidergic chemokine receptor CXCR3 and resulted
in the synthesis and characterization of five new azobenzene-
containing CXCR3 ligands. G protein activation assay and real-time
electrophysiology experiments demonstrated a photoswitching from
antagonism to partial agonism and even to full agonism (VUF16216).
SAR evaluation suggests that the size and electron-donating
properties of the inner aromatic ring substituents are important for
the efficacy photoswitching. These azo compounds are the first
GPCR ligands with a nearly full efficacy photoswitch and may
become valuable pharmacological tools for the optical control of
peptidergic GPCR signaling.
the efficacy for a peptidergic G protein-coupled receptor can be
controlled with light from antagonism to partial and,
unprecedentedly, to full agonism.
To develop this proof of concept in GPCRs, we selected
chemokine receptor CXCR3, which belongs to the class A
GPCRs and is of interest since it plays a key role in T cell
function and CXCR3 agonism can aid in tissue repair.[5] CXCR3
signals via Gαi proteins in response to the endogenous agonist
peptide ligands CXCL9, CXCL10 and CXCL11.[6] However,
small-molecule CXCR3 agonists are scarce and limited to
peptidomimetic ligands[7] and non-peptidomimetic biaryl-type
ligands.[8] Structure-activity relationship studies on the latter
revealed that increasing the size of a halogen substituent on the
ortho position of the outer aryl ring increases the agonist efficacy,
while shifting it to the meta position yields antagonists (figure
1A).[8] Quantitative structure-activity relationships suggested that
the electron density, a possible halogen bond and/or geometrical
differences as a result of the biaryl dihedral angle contribute to
the agonist efficacies.[8] Here, we aim to mimic this molecular
efficacy hotspot by azologization of the biaryl moiety and as
such enable optical control over efficacy of the CXCR3 ligands.
Photopharmacology is an emerging discipline that involves the
dynamic regulation of protein activity with light. Amongst others,
freely diffusible photoswitchable ligands are used to regulate
protein activity in a non-invasive and reversible manner with high
spatiotemporal precision.[1] A commonly used strategy is to
incorporate an azobenzene moiety into an existing bioactive
ligand (azologization[1a]) to enable the isomerization from a
planar trans configuration to a bent cis configuration in response
to near-UV light. Longer wavelengths or thermal relaxation can
revert this photoisomerization, offering a dynamic approach to
modulate ligand geometry. These geometrical changes can alter
the binding affinity and/or efficacy of the ligand for its target
protein.
In view of their important role in numerous (patho)physiological
processes and high therapeutic relevance, GPCRs represent an
excellent protein class for the development of photoswitchable
ligands.[2] Recently, several photoswitchable ligands have been
reported for GPCRs[3] with some examples involving in vivo
use.[4] Although it is not always straightforward to discern
contributions by affinity or potency shift from the contribution by
any efficacy shift, most reported photoswitchable GPCR ligands
display light-induced alterations in affinity or potency. We
Figure 1: General design strategy. (A) Example of biaryl CXCR3 ligands that
show differences in efficacy based on position and size of
a halogen
substituent. (B) Azologization of the scaffold of the biaryl CXCR3 ligands with
maintained ortho-Br atom and tailored Y groups to give photoisomerizable
analogs of 1a-d (i.e. 2a-f). Illumination with 360 nm enables a switch from
trans to cis configuration and 434 nm illumination reverts the
photoisomerization.
present here
a detailed photochemical and biochemical
characterization of a class of photoswitchable ligands, of which
[*]
Dr. X. Gómez-Santacana, Dr. S. M. de Munnik, P. Vijayachandran,
D. Da Costa Pereira, J. P. M. Bebelman, Prof. Dr. I. J. P. de Esch,
Dr. H. F. Vischer, Dr. Maikel Wijtmans, Prof. Dr. Rob Leurs
Division of Medicinal Chemistry
A series of azobenzene-containing ligands was synthesized by
replacing the biaryl moiety of 1a-d with an azobenzene moiety to
obtain 2a-f (Scheme S1). The geometrical differences between
trans and cis azobenzene isomers were hypothesized to be able
to mimic the spatial features of the biaryl moiety in 1a-d. In all
cases, the bromine atom on the ortho position of the outer
aromatic ring was maintained to accommodate a potential
halogen bond that was suggested to be important for the
agonism of the parent biaryl ligands.[8] To explore the
Amsterdam Institute for Molecules Medicines and Systems (AIMMS)
Vrije Universiteit Amsterdam
De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
E-mail: m.wijtmans@vu.nl, r.leurs@vu.nl
Dr. X. Gómez-Santacana and Dr. S. M. de Munnik contributed
equally to this work
[a]
Supporting information for this article is given via a link at the end of
the document.
This article is protected by copyright. All rights reserved.

10.1002/anie.201804875
Angewandte Chemie International Edition
COMMUNICATION
contribution of a possible conformational lock and electron
density in the azobenzene-moiety to the targeted efficacy switch,
substituents on the para position of the inner aromatic ring (Y,
figure 1B and table 1) were varied. To that end, halogen atoms
of different sizes and electronegativity (F, Cl and Br) and two
different electron-donating groups (-OMe, -NMe2) were used.
Based on spatial considerations, agonism was hypothesized to
reside in the cis-isomer of these designed compounds.
analysis, only trans-2e was observed in the dark, while a PSS of
95% cis-2e after 360 nm illumination and a PSS of 75% trans-2e
after 434 nm back-illumination were identified. Compound 2e
displays high resistance toward photochemical wear (figure 2E)
and the long relaxation half-lives of cis 2a-e indicate the bistable
nature of 2a-e (figure 2B, table 1, figure S2).
Table 1. Photoisomerization properties and binding affinities of 2a-f for human
CXCR3. Percentage of photoisomerization, pIC50 values and photo-induced
affinity switches are shown as the mean ± standard error of the mean (SEM)
of at least three independent experiments each performed in triplicate.
Photoisomerization
[
125I]-CXCL10 binding[d]
Trans
λmax
(nm)
Cis
λmax
(nm)
[c]
t1/2
(d)
pIC50
trans
pIC50 at
PSS
[a]
[a]
#
Y
PSS[b] (%)
PAS[e]
1.0 ± 0.1
1.6 ± 0.0
2.0 ± 0.4
3.8 ± 0.4
8.3 ± 1.3
2a
2b
2c
2d
H
F
325
420
420
88.9 ± 0.4 109 6.0 ± 0.1 6.0 ± 0.1
327
331
334
353
387
92.7 ± 0.1
92.6 ± 0.2
92.6 ± 0.2
92.1 ± 0.1
dec.[f]
92
55
6.0 ± 0.0 6.2 ± 0.0
5.9 ± 0.1 6.2 ± 0.1
5.8 ± 0.1 6.4 ± 0.1
5.9 ± 0.0 6.8 ± 0.0
Cl
Br
419
424
61
2e OMe
2f NMe2
428
dec.[f]
29
dec.[f]
[a] The absorbance maxima were extracted from UV-Vis spectra (10 µM in
HEPES buffer with 1% DMSO at 25 °C, figure 2A, figure S1). [b] The
photostationary state (PSS) was measured as the percentage of area of the
cis isomer compared to combined areas of cis and trans isomers as detected
by LC at 265 nm. [c] The thermal relaxation half-life was determined by
allowing a PSS sample (10 µM in HEPES buffer with 1% DMSO) to thermally
isomerize at 25 °C in the dark (figure S2). [d] The pIC50 value was measured
by
[
125I]-CXCL10 binding experiments using membranes prepared from
HEK293T cells expressing CXCR3. [e] The photo-induced affinity switch
(PAS) was calculated as the ratio of the IC50 values of trans isomers and those
corresponding to the PSS. [f] dec. = decomposition under illumination at 360
nm
Figure 2. Photochemical properties of 2e. (A) UV-Vis absorption spectra of 10
µM 2e in HEPES buffer with 1% DMSO at 25 °C under dark conditions (black),
after illumination with 360 nm light for 2 min (magenta) and after back-
illumination for 2 min with 434 nm light (turquoise). (B) UV-Vis absorption
spectra of 10 µM 2e in HEPES buffer after obtaining the PPS, measured every
24 h during 30 d at 25 °C. (C, D) The isomerization of 1 mM 2e in DMSO-d6
analyzed by (C) 1H NMR (α-ammonium methylene protons with signals at 4.56
ppm and 4.31 ppm for the trans and cis isomers, respectively) and (D) LC-MS
analyses. (E) UV-Vis absorption measurements at 360 nm after repeated
cycles of illumination with 360 nm (magenta) and 434 nm light (turquoise) of
10 µM 2e in HEPES buffer.
First, the photochemical properties of 2a-f were investigated by
determining the UV-Vis absorption spectra after illumination
(table 1). In the dark, the trans isomers were identified (table 1,
figure 2A, figure S1). Depending on the electron donating
properties of the Y substituent (table 1), a slight red-shifting in
wavelengths of maximal absorbance of the π–π* band was
observed. Upon illumination with 360 nm light, mainly the cis
isomers of 2a-e were observed (figure 2A, figure S1A-D),
showing suitable photostationary states (PSS) containing 89-
93% cis isomer (table 1). After subsequent illumination of the
samples with 434 nm light, mostly trans isomers of 2a-e were
detected (figure 2A, figure S1A-D). Unfortunately, 2f
decomposes under 360 nm illumination (figure S1E) and was
therefore omitted from further pharmacological characterization.
Compounds 2a-e were tested for their ability to bind to CXCR3.
Control 1a inhibits
[
125I]-CXCL10 binding to membranes
prepared from CXCR3-expressing cells with a pIC50 value of 6.4
± 0.1, which is comparable to previous findings.[8] Compounds
2a-e were tested in the dark (corresponding to >99% trans
isomers) and at PSS after illumination during 15 minutes with
360 nm light. Due to the bistable nature of 2a-e, the
1
Photoisomerization of 2e was confirmed by H NMR (figure 2C)
and LC-MS (figure 2D) analyses. In both LC-MS and NMR
This article is protected by copyright. All rights reserved.

10.1002/anie.201804875
Angewandte Chemie International Edition
COMMUNICATION
photostationary state was assumed to remain unaltered after
consequently shows the largest photo-induced difference of
illumination during the assay time. All trans isomers of 2a-e
inhibit
efficacy (PDE, table 2).
[ a concentration-dependent
125I]-CXCL10 binding in
manner with similar submicromolar IC50 values (table 1, figure
3A). On the contrary, 2a-e illuminated to PSS demonstrate
increased pIC50 values with increasing size and electron
donating properties of substituent Y (table 1, figure 3A). For
example, 2a shows no photo-induced affinity shifts (PAS) upon
illumination, whereas 2e displays the largest PAS with an 8-fold
higher pIC50 value at PSS as compared to its trans form (table 1).
A [35S]-GTPγS functional binding assay was used to measure
the intrinsic activity (α) as a means to quantify the efficacy of
these photoswitchable ligands. As CXCL11 has the highest
potency and efficacy of all three chemokines[9], it was deemed
the best chemokine control for functional assays. Control 1d
(VUF11222) acts as a full agonist as compared to CXCL11
(figure S3A-B), as was previously reported[8]. We did not
observe any alteration of potency or efficacy of 1d as a result of
illumination (table 2, figure S3B). All trans compounds 2a-e act
as antagonists or very weak partial agonists with low efficacies
(figure 3C, table 2, figure S3C-F). On the other hand, 2a-d
illuminated to PSS act as partial agonists with comparable
submicromolar potencies (table 2, figure S3C-F). The efficacy of
2a-d at PSS qualitatively correlates with the size and the
electron donating properties of the para substituent (Y) of the
inner aromatic ring (figure 3B, table 2). Confirming this trend, 2e
at PSS acts as a full agonist (α=0.99, table 2, figure 3C) and
Table 2. Efficacy and potency of 2a-e and control 1d determined by [35S]-
GTPγS binding experiments using membranes prepared from HEK293T cells
expressing human CXCR3. Potency, intrinsic activity and values for PDE are
shown as the mean ± SEM of three independent experiments each performed in
duplicate.
Cpd.
1d
α[a] trans
α[a] at PSS
PDE[b]
pEC50 trans pEC50 at PSS
Y
-
1.04 ± 0.08 1.03 ± 0.07 0.00 ± 0.03
0.05 ± 0.03 0.30 ± 0.01 0.25 ± 0.02
0.12 ± 0.00 0.41 ± 0.03 0.30 ± 0.03
0.11 ± 0.01 0.54 ± 0.01 0.42 ± 0.01
0.14 ± 0.02 0.58 ± 0.05 0.45 ± 0.04
6.9 ± 0.0
6.9 ± 0.0
6.5 ± 0.1
6.2 ± 0.1
6.3 ± 0.1
6.2 ± 0.1
6.4 ± 0.1
[c]
2a
H
F
-
[c]
2b
-
[c]
2c
Cl
Br
-
[c]
2d
-
[c]
2e OMe 0.16 ± 0.01 0.99 ± 0.04 0.83 ± 0.06
-
[a] The ligand intrinsic activity (α) was determined relative to the maximum
response of the endogenous full agonist CXCL11 (for which α is set to 1.0). [b]
The photo-induced difference of efficacy (PDE) is obtained from subtracting the
intrinsic activity under dark conditions from the intrinsic activity at PSS. [c] Could
not be determined due to too low efficacy and/or potency.
Figure 3. Pharmacological characterization of 2a-e. (A) Binding experiments with [125I]-CXCL10 were performed in the presence of increasing concentrations of
2e in the dark (turquoise) or at PSS after 360 nm illumination (magenta) using membranes prepared from HEK293T cells expressing human CXCR3. (B, C)
Maximum responses (efficacy) of 1d and 2a-e after 360 nm illumination (B) or concentration-response curves of trans-2e and 2e at PSS (C), as determined in a
[
35S]-GTPγS binding experiment using membranes prepared from HEK293T cells expressing human CXCR3. Data are presented as percentage of specific [125I]-
CXCL10 binding (A) or as percentage of the maximum response induced by the endogenous agonist CXCL11 (B, C) and represent the mean ± SEM from at least
three independent experiments each performed in triplicate (A) or duplicate (B, C). (D, E) Representative traces of two-electrode voltage clamp experiments in
Xenopus laevis oocytes expressing human CXCR3 and GIRK channel in the presence of 2e (10 µM) (D) or 2e (10 µM) in competition with 1d (1 µM) (E) and
using 360 nm (magenta) and 434 nm light (turquoise) illumination cycles (concentrations given are in high potassium solution with 0.1% DMSO).
This article is protected by copyright. All rights reserved.

10.1002/anie.201804875
Angewandte Chemie International Edition
COMMUNICATION
role[5]. Further efforts will be undertaken to understand the
mechanism of action of these compounds and improve their
biocompatible properties, (e.g. red-shifting photoisomerization
wavelengths).[15] To our knowledge, 2a-e are the first small-
To address the possibility of nonspecific effects on the receptor
activity due to compound microprecipitation,[10] nephelometry
experiments were performed (figure S5)[11] and revealed no
microprecipitation of trans-2a-e or cis-2a-e at pharmacologically
relevant concentrations.
molecule GPCR ligands that harbor
a rationally designed
efficacy photoswitch. Moreover, 2e (VUF16216) is the highest
photo-induced efficacy switch for a GPCR ligand reported to
date and provides a real-time efficacy switch from antagonism to
agonism. Our results together with other reported GPCR efficacy
photoswitchers may contribute to the development of a second
generation of photoswitchable ligands with light-dependent
functional activity switches.
The full agonism of 2e at PSS can possibly be explained by the
size of the -OMe group in Y position and/or the more important
electron-donating properties as compared to the halogen
substituents. Unfortunately, this explanation could not be further
explored with a -NMe2 moiety due to chemical instability of 2f
under illumination. We observed a correlation between PDE and
PAS values (r = 0.986, P = 0.0024, figure S4). This is probably a
result of more efficient inhibition of [125I]-CXCL10 binding by
photoisomers with higher efficacy through preferential binding to
a subset of CXCR3 conformations that overlap with those
Acknowledgements
preferentially binding the endogenous agonist [125I]-CXCL10[12]
.
All authors acknowledge the Netherlands Organisation for
Scientific Research for financial support (TOPPUNT, “7 ways to
7TMR modulation (7-to-7)”, 718.014.002). We thank Danny
Scholten, Chris de Graaf, Shanliang Sun and Luc Roumen for
helpful discussions, Hans Custers for recording HRMS spectra
and Mounir Andaloussi for providing 4.
The photo-induced efficacy switch of 2e was dynamically
evaluated in real-time electrophysiology measurements using
two-electrode voltage clamp (TEVC) in Xenopus laevis oocytes
transiently co-expressing CXCR3 and
G
protein-coupled
inwardly-rectifying potassium (GIRK) channel. Control agonist
1d induced GIRK channel activation, which was not affected by
several illumination cycles of 360 nm and 434 nm light, and the
initial current was restored upon washing-out with buffer (not
shown). Trans-2e did not activate GIRK channels (figure 3D), as
expected for an antagonist/weak partial agonist, but a slight
outward current was observed. Indeed, it is well known that
quaternary ammonium ions may interact with GIRK channels[13]
or other potassium channels[14]. Illumination of perfused oocytes,
expressing CXCR3 and GIRK with 360 nm light prompted the
photoisomerization of trans-2e to the cis configuration, and
consequently induced the activation of CXCR3 in turn leading to
GIRK channel activation (figure 3D). This confirms CXCR3
agonism of 2e at PSS in the oocyte expression system. This
effect could be reverted by 434 nm illumination and repeated
cycles of illumination with 360 and 434 nm light clearly show the
reversible activation of CXCR3 by photoswitching trans-2e to its
cis isomer and vice versa (figure 3D). The antagonist behaviour
of trans-2e was confirmed by competition with agonist 1d in the
same CXCR3-expressing oocyte system (figure 3E). In the dark,
trans-2e antagonized the CXCR3 activation induced by 1d and
this was reverted upon illumination with 360 nm light.
Subsequent illumination with 434 nm recovered the antagonism
of trans-2e.
Taken together, we have demonstrated optical control of CXCR3
activity by photoswitching small-molecule antagonists/weak
partial agonists to agonists with different efficacies up to full
agonism. The isomerization from the trans to cis configuration
was designed to probe a very subtle efficacy hotspot that was
identified in earlier studies. Real-time electrophysiology
measurements confirmed the reversibility of an efficacy switch
from antagonism to agonism upon several illumination cycles.
These compounds, particularly 2e, will be excellent tool
compounds to elucidate CXCR3 signaling due to the distinctive
spatio-temporal control of functional activity provided with light.
Such photocontrol may also be of interest for topical treatments,
such as wound healing where CXCR3 agonism plays a key
Keywords: Azo compound • Efficacy Photoswitching • G
Protein-Coupled Receptor • Photochromism •
Photopharmacology
[1]
a) J. Broichhagen, J. A. Frank, D. Trauner, Acc. Chem. Res. 2015, 48,
1947-1960; b) M. M. Lerch, M. J. Hansen, G. M. van Dam, W.
Szymanski, B. L. Feringa, Angew. Chem. Int. Ed. Engl. 2016, 55,
10978-10999; Angew. Chem. 2016, 128, 11140; c) A. A. Beharry, G. A.
Woolley, Chem. Soc. Rev. 2011, 40, 4422-4437.
[2]
[3]
A. S. Hauser, M. M. Attwood, M. Rask-Andersen, H. B. Schioth, D. E.
Gloriam, Nat. Rev. Drug Discov. 2017, 16, 829-842.
a) M. Schonberger, D. Trauner, Angew. Chem. Int. Ed. Engl. 2014, 53,
3264-3267; Angew. Chem. 2014, 126, 3329; b) S. Pittolo, X. Gomez-
Santacana, K. Eckelt, X. Rovira, J. Dalton, C. Goudet, J. P. Pin, A.
Llobet, J. Giraldo, A. Llebaria, P. Gorostiza, Nat. Chem. Biol. 2014, 10,
813-815; c) M. I. Bahamonde, J. Taura, S. Paoletta, A. A. Gakh, S.
Chakraborty, J. Hernando, V. Fernandez-Duenas, K. A. Jacobson, P.
Gorostiza, F. Ciruela, Bioconjug. Chem. 2014, 25, 1847-1854; d) J.
Broichhagen, N. R. Johnston, Y. von Ohlen, H. Meyer-Berg, B. J. Jones,
S. R. Bloom, G. A. Rutter, D. Trauner, D. J. Hodson, Angew. Chem. Int.
Ed. Engl. 2016, 55, 5865-5868; Angew. Chem. 2016, 128, 5961; e) L.
Agnetta, M. Kauk, M. C. A. Canizal, R. Messerer, U. Holzgrabe, C.
Hoffmann, M. Decker, Angew. Chem. Int. Ed. Engl. 2017, 56, 7282-
7287; Angew. Chem. 2017, 129, 7388; f) M. V. Westphal, M. A.
Schafroth, R. C. Sarott, M. A. Imhof, C. P. Bold, P. Leippe, A.
Dhopeshwarkar, J. M. Grandner, V. Katritch, K. Mackie, D. Trauner, E.
M. Carreira, J. A. Frank, J. Am. Chem. Soc. 2017, 139, 18206-18212;
g) N. J. Hauwert, T. A. M. Mocking, D. Da Costa Pereira, A. J. Kooistra,
L. M. Wijnen, G. Vreeker, N. W. E. Verweij, B. H. De Boer, M. J. Smit,
C. de Graaf, H. F. Vischer, I. J. P. De Esch, M. Wijtmans, R. Leurs, J.
Am. Chem. Soc. 2018, DOI: 10.1021/jacs.1027b11422.
[4]
a) M. H. Berry, A. Holt, J. Levitz, J. Broichhagen, B. M. Gaub, M. Visel,
C. Stanley, K. Aghi, Y. J. Kim, K. Cao, R. H. Kramer, D. Trauner, J.
Flannery, E. Y. Isacoff, Nat. Commun. 2017, 8, 1862; b) X. Gomez-
Santacana, S. Pittolo, X. Rovira, M. Lopez, C. Zussy, J. A. Dalton, A.
Faucherre, C. Jopling, J. P. Pin, F. Ciruela, C. Goudet, J. Giraldo, P.
Gorostiza, A. Llebaria, ACS Cent. Sci. 2017, 3, 81-91; c) C. Zussy, X.
Gomez-Santacana, X. Rovira, D. De Bundel, S. Ferrazzo, D. Bosch, D.
Asede, F. Malhaire, F. Acher, J. Giraldo, E. Valjent, I. Ehrlich, F.
This article is protected by copyright. All rights reserved.

10.1002/anie.201804875
Angewandte Chemie International Edition
COMMUNICATION
Ferraguti, J. P. Pin, A. Llebaria, C. Goudet, Mol. Psychiatry 2018, 23,
[10] M. F. Sassano, A. K. Doak, B. L. Roth, B. K. Shoichet, J. Med. Chem.
2013, 56, 2406-2414.
509-520.
[5]
A. C. Huen, A. Wells, Adv. Wound Care (New Rochelle) 2012, 1, 244-
248.
[11] K. A. Dehring, H. L. Workman, K. D. Miller, A. Mandagere, S. K. Poole,
J. Pharm. Biomed. Anal. 2004, 36, 447-456.
[6]
[7]
J. R. Groom, A. D. Luster, Exp. Cell. Res. 2011, 317, 620-631.
M. Wijtmans, D. Scholten, W. Mooij, M. J. Smit, I. J. P. de Esch, C. de
Graaf, R. Leurs, in Chemokines: Chemokines and Their Receptors in
Drug Discovery (Ed.: N. Tschammer), Springer International Publishing,
Cham, 2015, pp. 119-185.
[12] M. A. Cox, C. H. Jenh, W. Gonsiorek, J. Fine, S. K. Narula, P. J.
Zavodny, R. W. Hipkin, Mol. Pharmacol. 2001, 59, 707-715.
[13] R. Andrade, Eur. J. Pharmacol. 1991, 199, 259-262.
[14] M. Zhou, J. H. Morais-Cabral, S. Mann, R. MacKinnon, Nature 2001,
411, 657-661.
[8]
[9]
M. Wijtmans, D. J. Scholten, L. Roumen, M. Canals, H. Custers, M.
Glas, M. C. Vreeker, F. J. de Kanter, C. de Graaf, M. J. Smit, I. J. de
Esch, R. Leurs, J. Med. Chem. 2012, 55, 10572-10583.
C. E. Heise, A. Pahuja, S. C. Hudson, M. S. Mistry, A. L. Putnam, M. M.
Gross, P. A. Gottlieb, W. S. Wade, M. Kiankarimi, D. Schwarz, P.
Crowe, A. Zlotnik, D. G. Alleva, J Pharmacol Exp Ther 2005, 313,
1263-1271.
[15] a) M. Dong, A. Babalhavaeji, S. Samanta, A. A. Beharry, G. A. Woolley,
Acc. Chem. Res. 2015, 48, 2662-2670; b) D. Bleger, S. Hecht, Angew.
Chem. Int. Ed. Engl. 2015, 54, 11338-11349; Angew. Chem. 2015, 127,
11494.
This article is protected by copyright. All rights reserved.

10.1002/anie.201804875
Angewandte Chemie International Edition
COMMUNICATION
Entry for the Table of Contents
COMMUNICATION
Xavier Gómez-Santacana[a], Sabrina M.
de Munnik[a], Prashanna
Vijayachandran, Daniel Da Costa
Pereira, Jan Paul M. Bebelman, Iwan J.
P. de Esch, Henry F. Vischer, Maikel
Wijtmans*, Rob Leurs*
Page No. – Page No.
In order to obtain unprecedented spatiotemporal optical control of GPCRs, we set
out to develop efficacy photoswitchable ligands. G protein activation assays and
real-time electrophysiology experiments validated a photoswitching from
antagonism to partial agonism and even to full agonism. VUF16216 is the first
GPCR azo-ligand with almost full efficacy photoswitch and it may become a
valuable tool for the optical control of GPCR activity.
Photoswitching the efficacy of a
small-molecule ligand for a
peptidergic GPCR: from antagonism
to agonism
This article is protected by copyright. All rights reserved.