Designing inhibitors of cytochrome c/cardiolipin peroxidase complexes: mitochondria-targeted imidazole-substituted fatty acids.
Mitochondria have emerged as the major regulatory platform responsible for the coordination of numerous metabolic reactions as well as cell death processes, whereby the execution of intrinsic apoptosis includes the production of reactive oxygen species fueling oxidation of cardiolipin (CL) catalyzed by cytochrome (Cyt) c. As this oxidation occurs within the peroxidase complex of Cyt c with CL, the latter represents a promising target for the discovery and design of drugs with antiapoptotic mechanisms of action. In this work, we designed and synthesized a new group of mitochondria-targeted imidazole-substituted analogs of stearic acid TPP-n-ISAs with various positions of the attached imidazole group on the fatty acid (n = 6, 8, 10, 13, and 14). By using a combination of absorption spectroscopy and EPR protocols (continuous wave electron paramagnetic resonance and electron spin echo envelope modulation) we demonstrated that TPP-n-ISAs indeed were able to potently suppress CL-induced structural rearrangements in Cyt c, paving the way to its peroxidase competence. TPP-n-ISA analogs preserved the low-spin hexa-coordinated heme-iron state in Cyt c/CL complexes whereby TPP-6-ISA displayed a significantly more effective preservation pattern than TPP-14-ISA. Elucidation of these intermolecular stabilization mechanisms of Cyt c identified TPP-6-ISA as an effective inhibitor of the peroxidase function of Cyt c/CL complexes with a significant antiapoptotic potential realized in mouse embryonic cells exposed to ionizing irradiation. These experimental findings were detailed and supported by all-atom molecular dynamics simulations. Based on the experimental data and computation predictions, we identified TPP-6-ISA as a candidate drug with optimized antiapoptotic potency.
['Jiang|Jianfei|J|', 'Bakan|Ahmet|A|', 'Kapralov|Alexandr A|AA|', 'Ishara Silva|K|K|', 'Huang|Zhentai|Z|', 'Amoscato|Andrew A|AA|', 'Peterson|James|J|', 'Krishna Garapati|Venkata|V|', 'Saxena|Sunil|S|', 'Bayir|Hülya|H|', 'Atkinson|Jeffrey|J|', 'Bahar|Ivet|I|', 'Kagan|Valerian E|VE|']
D000818:Animals D017209:Apoptosis D002308:Cardiolipins D045304:Cytochromes c D015195:Drug Design D053595:Embryonic Stem Cells D004791:Enzyme Inhibitors D005720:Gamma Rays D006736:Horses D007093:Imidazoles D051379:Mice D008929:Mitochondria, Heart D056004:Molecular Dynamics Simulation D009943:Organophosphorus Compounds D009195:Peroxidase D010713:Phosphatidylcholines D012277:Ricinoleic Acids D013229:Stearic Acids D013329:Structure-Activity Relationship
Cytochrome c Electron paramagnetic resonance All-atom molecular dynamics simulation Cardiolipin peroxidation Free radicals Imidazole-substituted stearic acid Mitochondria targeting Peroxidase inhibitors Reactive intermediates