Figure 1.

Quantification of oxidation sensitivity of TRP channels. A) Chemical structures of reactive disulphides and the redox potentials (E_1/2) determined by rotating disk-electrode voltammetry. E_1/2 is an empirical value that is defined as the midpoint of the rise of current in voltammogram and, as such, it differs from the standard reduction potential (E⁰) of the compound. E_1/2 values of 5 mM reactive disulphides dissolved in dehydrated DMSO were measured in 0.1 M Bu₄NBF₄/DMSO using a glassy carbon working electrode, a platinum wire counter electrode and an Ag/Ag⁺ reference electrode at room temperature. Modified from Takahashi et al.⁹⁰⁾ B) The chemical reaction of a reactive disulphide compound with a Cys sulfhydryl (upper) and the single electron redox reaction, for which we determined E_1/2 values by rotating disk-electrode voltammetry (lower). C) Oxidation sensitivity of TRP channels. Plots of maximum [Ca²⁺]_i rises (Δ[Ca²⁺]_i) induced by 10 µM reactive disulphides in HEK293 cells expressing redox-sensitive TRP channels against redox potentials of respective substances described in A). Modified from Takahashi et al.⁹⁰⁾