4 research outputs found
In Situ Laser-Induced Fabrication of a Ruthenium-Based Microelectrode for Non-Enzymatic Dopamine Sensing
No full textIn this paper, we propose a fast and simple approach for the fabrication of the electrocatalytically active ruthenium-containing microstructures using a laser-induced metal deposition technique. The results of scanning electron microscopy and electrical impedance spectroscopy (EIS) demonstrate that the fabricated ruthenium-based microelectrode had a highly developed surface composed of 10 μm pores and 10 nm zigzag cracks. The fabricated material exhibited excellent electrochemical properties toward non-enzymatic dopamine sensing, including high sensitivity (858.5 and 509.1 μA mM−1 cm−2), a low detection limit (0.13 and 0.15 μM), as well as good selectivity and stability
Optical Control of NMethyldaspartate Receptors by Azobenzene Quaternary Ammonium Compounds
No full textAzobenzene-based quaternary ammonium
compounds provide optical
control of ion channels and are considered promising agents for regulation
of neuronal excitability and for restoration of the photosensitivity
of retinal cells. However, the selectivity of the action of these
compounds remains insufficiently known. We studied the action of DENAQ
(diethylamine-azobenzene-quaternary ammonium) and DMNAQ (dimethylamine-azobenzene-quaternary
ammonium) on ionotropic glutamate receptors in rat brain neurons.
In the dark, both compounds applied extracellularly caused fast and
reversible inhibition of NMDA (N-methyl-d-aspartate) receptor-mediated currents with IC50 values
of 10 and 5 μM, respectively. Light-induced transformation of
DENAQ and DMNAQ to their cis forms caused the IC50 values to increase to 30 and 27 μM, respectively.
Detailed analysis of this action revealed a complex nature consisting
of fast inhibitory and slower potentiating effects. The AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic
acid) receptors were only weakly affected independently on illumination.
We conclude that, in addition to their long-lasting intracellular
action, which persists after washout, azobenzene-based quaternary
ammonium compounds should affect glutamatergic transmission and synaptic
plasticity during treatment. Our findings also extend the list of
soluble photoswitchable inhibitors of NMDA receptors. While the site(s)
and mechanisms of action are unclear, the effect of DENAQ demonstrates
strong pH dependence. At acidic pH values, DENAQ potentiates both
NMDA and AMPA receptors
Molecular mechanisms of adaptation to the habitat depth in visual pigments of A. subulata and L. forbesi squids: on the role of the S270F substitution: DOI: 10.5584/jiomics.v9i1.273
No full textRevealing the mechanisms of animal adaptation to different habitats is one of the central tasks of evolutionary physiology. A particular case of such adaptation is the visual adaptation of marine species to different depth ranges. Because water absorbs more intensively longer wavelengths than shorter wavelengths, the increase of habitat depth shifts the visual perception of marine species towards the blue region. In this study, we investigated the molecular mechanisms of such visual adaptation for two squid species – Alloteuthis subulata and Loligo forbesi. These species live at different depths (200 m and 360 m, respectively) and the absorption maximum of A. subulata visual rhodopsin is slightly red-shifted compared to L. forbesi rhodopsin (499 and 494 nm, respectively). Previously, the amino acid sequences of these two species were found to differ in 22 sites with only seven of them being non-neutral substitutions, and the S270F substitution was proposed as a possible candidate responsible for the spectral shift. In this study, we constructed computational models of visual rhodopsins of these two squid species and determined the main factors that cause the 5 nm spectral shift between the two proteins. We find that the origin of this spectral shift is a consequence of a complex reorganization of the protein caused by at least two mutations including S270F. Moreover, the direct electrostatic effect of polar hydroxyl-bearing serine that replaces non-polar phenylalanine is negligible due to the relatively long distance to the chromophore
Azobenzene/Tetraethyl Ammonium Photochromic Potassium Channel Blockers: Scope and Limitations for Design of Para-Substituted Derivatives with Specific Absorption Band Maxima and Thermal Isomerization Rate
No full textAzobenzene/tetraethyl ammonium photochromic ligands (ATPLs) are photoactive compounds with a large variety of photopharmacological applications such as nociception control or vision restoration. Absorption band maximum and lifetime of the less stable isomer are important characteristics that determine the applicability of ATPLs. Substituents allow to adjust these characteristics in a range limited by the azobenzene/tetraethyl ammonium scaffold. The aim of the current study is to find the scope and limitations for the design of ATPLs with specific spectral and kinetic properties by introducing para substituents with different electronic effects. To perform this task we synthesized ATPLs with various electron acceptor and electron donor functional groups and studied their spectral and kinetic properties using flash photolysis and conventional spectroscopy techniques as well as quantum chemical modeling. As a result, we obtained diagrams that describe correlations between spectral and kinetic properties of ATPLs (absorption maxima of E and Z isomers of ATPLs, the thermal lifetime of their Z form) and both the electronic effect of substituents described by Hammett constants and structural parameters obtained from quantum chemical calculations. The provided results can be used for the design of ATPLs with properties that are optimal for photopharmacological applications
