A simple adaptation to a protein crystallography station to facilitate difference X-ray scattering studies

The X-ray crystallography station I911-2 at MAXLab II (Lund, Sweden) has been adapted to enable difference small- and wide-angle X-ray scattering (SAXS/WAXS) data to be recorded. Modifications to the beamline included a customized flow cell, a motorized flow cell holder, a helium cone, a beam stop, a sample stage and a sample delivery system. This setup incorporated external devices such as infrared lasers, LEDs and reaction mixers to induce conformational changes in macromolecules. This platform was evaluated through proof-of-principle experiments capturing light-induced conformational changes in phytochromes. A difference WAXS signature of conformational changes in a plant aquaporin was also demonstrated using caged calcium.

Design and Synthesis of Two-Photon Responsive Chromophores for Near-Infrared Light-Induced Uncaging Reactions

Near-infrared two-photon (TP)-induced photorelease (uncaging) of bioactive molecules such as drugs has attracted considerable attention because of its ability to elucidate mechanistic aspects of biological processes. This short review summarizes recent developments in the design and synthesis of TP-responsive chromophores.1 Introduction2 Molecular Design of TP-Responsive Organic Chromophores for ‘Caging & Uncaging’2.1 π-Conjugation2.2 A Dipolar System2.3 A Quadrupolar System2.4 An Octupolar System3 Recent Developments of TP Uncaging Reactions3.1 4-Methoxy-7-nitroindolinyl Caged Auxins3.2 Uncaging of GABA and Tryptophan Using TP-Induced Electron-Transfer Reactions3.3 Effect of Position Isomery in Aminoquinoline-Derived Photolabile Protecting Groups (PPGs)3.4 Cooperative Dyads for TP Uncaging3.5 Caged Calcium with a Bis-styrylthiophene Backbone3.6 Cloaked Caged Compounds3.7 Three-Dimensional Control of DNA Hybridization by Orthogonal Two-Color TP Uncaging3.8 TP-Induced Release of Diethyl Phosphate (DEP) and ATP4 Our Contribution to TP Uncaging Reactions5 Summary

Visible light initiated release of calcium ions through photochemical electron transfer reactions

Visible light, photocatalytic, oxidation of EDTA to release caged calcium ions.

Calcium-activated chloride channels in the apical region of mouse vomeronasal sensory neurons

The rodent vomeronasal organ plays a crucial role in several social behaviors. Detection of pheromones or other emitted signaling molecules occurs in the dendritic microvilli of vomeronasal sensory neurons, where the binding of molecules to vomeronasal receptors leads to the influx of sodium and calcium ions mainly through the transient receptor potential canonical 2 (TRPC2) channel. To investigate the physiological role played by the increase in intracellular calcium concentration in the apical region of these neurons, we produced localized, rapid, and reproducible increases in calcium concentration with flash photolysis of caged calcium and measured calcium-activated currents with the whole cell voltage-clamp technique. On average, a large inward calcium-activated current of −261 pA was measured at −50 mV, rising with a time constant of 13 ms. Ion substitution experiments showed that this current is anion selective. Moreover, the chloride channel blockers niflumic acid and 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid partially inhibited the calcium-activated current. These results directly demonstrate that a large chloride current can be activated by calcium in the apical region of mouse vomeronasal sensory neurons. Furthermore, we showed by immunohistochemistry that the calcium-activated chloride channels TMEM16A/anoctamin1 and TMEM16B/anoctamin2 are present in the apical layer of the vomeronasal epithelium, where they largely colocalize with the TRPC2 transduction channel. Immunocytochemistry on isolated vomeronasal sensory neurons showed that TMEM16A and TMEM16B coexpress in the neuronal microvilli. Therefore, we conclude that microvilli of mouse vomeronasal sensory neurons have a high density of calcium-activated chloride channels that may play an important role in vomeronasal transduction.