Department of Biophysics, Benito Juarez Road, University of Delhi South Campus, New Delhi, 110021, India.
Department of Biophysics, Benito Juarez Road, University of Delhi South Campus, New Delhi, 110021, India.
Biochimie. 2023 Jun;209:150-160. doi: 10.1016/j.biochi.2023.02.005. Epub 2023 Feb 11.
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.
线粒体是细胞中过氧化氢（HO）的主要来源，HO 是一种活性氧物质。线粒体产生的活性氧物质氧化包括电压依赖性阴离子通道（VDAC）在内的主要蛋白质。我们想知道存在于线粒体周围的抗氧化剂如何对抗 HO 的作用。N-乙酰-L-半胱氨酸（NAC）是细胞中天然存在的抗氧化剂。有鉴于此，通过体外电生理研究研究了抗氧化剂 NAC 对 HO 氧化 VDAC 的调节作用。首先，研究了 HO 和 NAC 对独立掺入的单通道 VDAC 的影响。结果表明，NAC 以半最大抑制浓度（IC）约 1.04 μM 抑制 VDAC 电导。相比之下，HO 增强了 VDAC 电导。后来，HO 诱导的氧化应激使 VDAC 增加的电导具有半最大有效浓度（EC）约 302 nM。在 HO 处理（300 nM）VDAC 上施加 1 μM NAC 逆转了氧化作用。在下一步中，以相反的顺序添加 NAC 和 HO。当使用 HO 诱导氧化应激时，NAC 对电导的降低为 4.5±0.404 nS。电导变化接近 6.3%。然而，如果首先孵育抗氧化剂 NAC，然后再用 HO 处理，则 VDAC 的电导为 3.09±0.27 nS。电导变化接近 33%。HO 和 NAC 也影响 VDAC 的各种导通状态。计算机模拟研究表明，NAC 结合在 VDAC 的赖氨酸和谷氨酸上。因此，由于 NAC 与 HO 诱导的氧化应激引起的 VDAC 结合牢固，因此发现 NAC 对 VDAC 具有保护作用。
