title: Designing inhibitors of cytochrome c/cardiolipin peroxidase complexes: mitochondria-targeted imidazole-substituted fatty acids.
abstract: 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.
authors.affiliation: Center for Free Radical and Antioxidant Health and Center for Medical Countermeasures against Radiation, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Jianfei
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Department of Computational and System Biology, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Bakan
authors.affiliation: Center for Free Radical and Antioxidant Health and Center for Medical Countermeasures against Radiation, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Alexandr A
authors.initials: AA
authors.lastname: Kapralov
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: K
authors.initials: K
authors.lastname: Ishara Silva
authors.affiliation: Center for Free Radical and Antioxidant Health and Center for Medical Countermeasures against Radiation, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Zhentai
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Center for Free Radical and Antioxidant Health and Center for Medical Countermeasures against Radiation, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Amoscato
authors.affiliation: Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: James
authors.initials: J
authors.lastname: Peterson
authors.affiliation: Department of Chemistry & Centre for Biotechnology, Brock University, St. Catharines, ON L2S 3A1, Canada.
authors.forename: Venkata
authors.initials: V
authors.lastname: Krishna Garapati
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Sunil
authors.initials: S
authors.lastname: Saxena
authors.affiliation: Center for Free Radical and Antioxidant Health and Center for Medical Countermeasures against Radiation, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Hülya
authors.initials: H
authors.lastname: Bayir
authors.affiliation: Department of Chemistry & Centre for Biotechnology, Brock University, St. Catharines, ON L2S 3A1, Canada.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Atkinson
authors.affiliation: Department of Computational and System Biology, University of Pittsburgh, Pittsburgh, PA 15219, USA.
authors.forename: Ivet
authors.initials: I
authors.lastname: Bahar
authors.affiliation: Center for Free Radical and Antioxidant Health and Center for Medical Countermeasures against Radiation, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Pharmacology and Chemical Biology, and University of Pittsburgh, Pittsburgh, PA 15219, USA; Department of Radiation Oncology, University of Pittsburgh, Pittsburgh, PA 15219, USA. Electronic address: kagan@pitt.edu.
authors.forename: Valerian E
authors.initials: VE
authors.lastname: Kagan
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002308:Cardiolipins / Q000737:chemistry; D045304:Cytochromes c / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D015195:Drug Design; D053595:Embryonic Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000528:radiation effects; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000494:pharmacology*; D005720:Gamma Rays; D006736:Horses; D007093:Imidazoles / Q000737:chemistry; D051379:Mice; D008929:Mitochondria, Heart / Q000187:drug effects / Q000201:enzymology; D056004:Molecular Dynamics Simulation; D009943:Organophosphorus Compounds / Q000737:chemistry; D009195:Peroxidase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D010713:Phosphatidylcholines / Q000737:chemistry; D012277:Ricinoleic Acids / Q000737:chemistry*; D013229:Stearic Acids / Q000737:chemistry*; D013329:Structure-Activity Relationship
chemical_list: C519576:1,1',2,2'-tetraoleoylcardiolipin; D002308:Cardiolipins; D004791:Enzyme Inhibitors; D007093:Imidazoles; D009943:Organophosphorus Compounds; D010713:Phosphatidylcholines; D012277:Ricinoleic Acids; D013229:Stearic Acids; C029899:imidazole; D045304:Cytochromes c; D009195:Peroxidase; C017251:1,2-oleoylphosphatidylcholine; C030521:ricinoleic acid
keywords: All-atom molecular dynamics simulation; Cardiolipin peroxidation; Cytochrome c; Electron paramagnetic resonance; Free radicals; Imidazole-substituted stearic acid; Mitochondria targeting; Peroxidase inhibitors; Reactive intermediates