Figure 1.

General elements for toxic mechanisms of inducing mitochondrial oxidative stress via heavy metals. Heavy metals (Ag⁺, Hg²⁺, Cd²⁺, Pb²⁺, As³⁺, and Sb³⁺) induce oxidative stress by blocking respiratory complexes with MPTP opening due to interacting with the thiol groups shown in the picture. Other metals (Tl⁺, Al³⁺, Ga³⁺, In³⁺, Cr⁶⁺, and U⁶⁺) inactivate these thiol groups by indirectly oxidizing them due to activation of the production of oxygen radicals (ROS and H₂O₂). Black arrows show the metal’s reaction with thiol groups (SH-). The MPTP induction by heavy metals is shown by the bold arrow. The induction of ROS and H₂O₂ is marked with a blue arrow. The ROS-induced oxidation of thiol groups is shown by red arrows. Pink arrows show the cytochrome c release into the intermembrane space due to the MPTP opening. Abbreviations: ADP, adenosine diphosphate; ANT, adenine nucleotide translocase; ATP, adenosine triphosphate; CI–CV, inner mitochondrial membrane complexes I–V; Cyt C, cytochrome C; ETC, electron transport chain; GSH, reduced glutathione; IMM, inner mitochondrial membrane; MPTP, mitochondrial permeability transition pore; ROS, reactive oxygen species; SH-, molecular thiol groups; ΔΨ_mito, inner membrane potential.