Voltage dependent anion channel and its interaction with N-acetyl-L-Cysteine (NAC) under oxidative stress on planar lipid bilayer.

Mitochondria are the major source of Hydrogen Peroxide (HO), a reactive oxygen species, in the cells. The reactive oxygen species generated by the mitochondria oxidize major proteins including Voltage Dependent Anion Channel (VDAC). We were interested to know how the effect of HO is countered by antioxidants present around the mitochondria. N-Acetyl-l-Cysteine (NAC) is a naturally existing antioxidant in the cells. Keeping this in view, the modulatory effect of antioxidant NAC on HO oxidized VDAC has been investigated through in vitro electrophysiological studies. First, the effect of HO and NAC was studied on independently incorporated single-channel VDAC. It was observed that NAC suppresses VDAC conductance with a half-maximal inhibitory concentration (IC) of ∼1.04 μM. In contrast, HO enhances VDAC conductance. Later, oxidative stress was induced by HO on VDAC increased conductance with half-maximal effective concentration (EC) of ∼302 nM. An application of 1 μM NAC on HO treated (300 nM) VDAC reversed the effect of oxidation. In the next step, NAC and HO were added in reverse order. When oxidative stress was induced using HO, reduction in conductance by NAC was 4.5 ± 0.404 nS. The change in conductance is nearly 6.3%. However, if antioxidant NAC was incubated first followed by HO treatment, the conductance of VDAC was 3.09 ± 0.27 nS. The change in conductance is near 33%. Both HO and NAC also affected various conducting states of VDAC. In-silico studies indicated the binding of NAC at Lysine and Glutamic acid of VDAC. Hence, NAC was found to be effective in protection of VDAC against HO-induced oxidative stress due to its strong binding.