Photomodulation of Ionic Current Through Hemithioindigo‐Modified Gramicidin Channels.

Lougheed, Tyler; Borisenko, Vitali; Hennig, Thomas; Rueck‐Braun, Karola; Woolley, G. Andrew

doi:10.1002/chin.200509195

Cited by 8 publications

(9 citation statements)

References 15 publications

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“…Because the orientation of the dipole depends on the position of the sulfonate group (above or below the plane of the xanthene ring), the dipole's orientation relative to the protein will differ between the two diastereoisomers by ;80°, assuming the xanthene ring of the BSR has the same orientation in the two diastereosiomers. Much smaller modulations of electric dipoles (changes # 3 Debye) have been shown to have significant effects on the ion channel gating of modified gramicidin (26,27). Since the more rigid BSR probe is likely to hold the dipole of the two diasteroisomers in more defined orientations relative to the protein than is the case for the diastereoisomers of the more flexible BR probe, it is at least feasible that the observed differences in Ca 21 affinity of the sNTnCÁBSR diastereoisomers could be attributed to this differential electric dipolar effect.…”

Section: Discussionmentioning

confidence: 99%

Toward Protein Structure In Situ: Comparison of Two Bifunctional Rhodamine Adducts of Troponin C

Julien

Sun

Knowles³

et al. 2007

Biophysical Journal

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As part of a program to develop methods for determining protein structure in situ, sTnC was labeled with a bifunctional rhodamine (BR or BSR), cross-linking residues 56 and 63 of its C-helix. NMR spectroscopy of the N-terminal domain of BSR-labeled sTnC in complex with Ca(2+) and the troponin I switch peptide (residues 115-131) showed that BSR labeling does not significantly affect the secondary structure of the protein or its dynamics in solution. BR-labeling was previously shown to have no effect on the solution structure of this complex. Isometric force generation in isolated demembranated fibers from rabbit psoas muscle into which BR- or BSR-labeled sTnC had been exchanged showed reduced Ca(2+)-sensitivity, and this effect was larger with the BSR label. The orientation of rhodamine dipoles with respect to the fiber axis was determined by polarized fluorescence. The mean orientations of the BR and BSR dipoles were almost identical in relaxed muscle, suggesting that both probes accurately report the orientation of the C-helix to which they are attached. The BSR dipole had smaller orientational dispersion, consistent with less flexible linkers between the rhodamine dipole and cysteine-reactive groups.

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Section: Discussionmentioning

confidence: 99%

Toward Protein Structure In Situ: Comparison of Two Bifunctional Rhodamine Adducts of Troponin C

Julien

Sun

Knowles³

et al. 2007

Biophysical Journal

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“…78 Intermediate wavelengths between the maximum and minimum fractional occupancy of the cis state can be used to control in an analog manner the balance between cis and trans, and thus the percent activation of the channel. 77 Besides azobenzene, other switches like spiropyran/merocyanine 79 and hemithioindigo 80 have advantages of their own and have been applied recently. Rather than simply controlling linker length or angle, these other switches can affect protein function by reversibly altering polarity.…”

Section: Iv1 Azobenzene-photoswitched Ion Channelsmentioning

confidence: 99%

“…Large changes in polarity also result from cis-trans photoisomerization of hemithioindigo compounds. 80 Several strategies have been devised to exploit lightreversible changes to activate and deactivate ion channels. These are represented in Fig.…”

Section: Iv1 Azobenzene-photoswitched Ion Channelsmentioning

confidence: 99%

Optical switches and triggers for the manipulation of ion channels and pores

Gorostiza

Isacoff

2007

Mol. BioSyst.

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Like fluorescence sensing techniques, methods to manipulate proteins with light have produced great advances in recent years. Ion channels have been one of the principal protein targets of photoswitched manipulation. In combination with fluorescence detection of cell signaling, this has enabled non-invasive, all-optical experiments on cell and tissue function, both in vitro and in vivo. Optical manipulation of channels has also provided insights into the mechanism of channel function. Optical control elements can be classified according to their molecular reversibility as non-reversible phototriggers where light breaks a chemical bond (e.g. caged ligands) and as photoswitches that reversibly photoisomerize. Synthetic photoswitches constitute nanoscale actuators that can alter channel function using three different strategies. These include (1) nanotoggles, which are tethered photoswitchable ligands that either activate channels (agonists) or inhibit them (blockers or antagonists), (2) nanokeys, which are untethered (freely diffusing) photoswitchable ligands, and (3) nanotweezers, which are photoswitchable crosslinkers. The properties of such photoswitches are discussed here, with a focus on tethered photoswitchable ligands. The recent literature on optical manipulation of ion channels is reviewed for the different channel families, with special emphasis on the understanding of ligand binding and gating processes, applications in nanobiotechnology, and with attention to future prospects in the field.

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“…40 Indigoid dyes [41][42][43][44][45] and foremost hemithioindigo (HTI) 46 have emerged as a very promising class of chromophores for photoswitching applications. HTI has been employed as photopharmacological tool, [47][48][49][50] for responsive supramolecular systems, [51][52][53][54] catalysis, 24 and advanced molecular machine building. 10,[55][56][57][58][59][60][61] The fundamental photochemistry of indigoid photoswitches has been explored in some detail, establishing rational design principles to consciously manipulate their properties.…”

Section: Introductionmentioning

confidence: 99%

All-Red-Light Photoswitching of Indirubin Controlled by Supramolecular Interactions

Thumser

Köttner

Hoffmann

et al. 2021

Preprint

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Red light responsiveness of photoswitches is a highly desired property for many important application areas such as biology or material sciences. The main approach to elicit this property uses strategic substitution of long known photoswitch motives such as azobenzenes or diarylethenes. Only very few photoswitches possess inherent red-light absorption of their core chromophore structures. Here we present a strategy to convert the long known purple indirubin dye into a prolific red light responsive photoswitch. In a supramolecular approach its photochromism can be changed from a negative to a positive one while at the same time significantly higher yields of the metastable E isomer are obtained. E to Z photoisomerization can then also be induced by red light of longer wavelengths. Indirubin therefore represents a unique example of reversible photoswitching using entirely red light for both switching directions.

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Photomodulation of Ionic Current Through Hemithioindigo‐Modified Gramicidin Channels.

Cited by 8 publications

References 15 publications

Toward Protein Structure In Situ: Comparison of Two Bifunctional Rhodamine Adducts of Troponin C

Toward Protein Structure In Situ: Comparison of Two Bifunctional Rhodamine Adducts of Troponin C

Optical switches and triggers for the manipulation of ion channels and pores

All-Red-Light Photoswitching of Indirubin Controlled by Supramolecular Interactions

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