ABSTRACT

Introduction...................................................................................................... 315 Oxidative Stress and Thiol-Disulfide Homeostasis......................................... 316 Sources of Reducing Power for Defensive Purposes in Mitochondria ........... 318 Enzyme-Bound Lipoic Acid as an Actor in Thiol Redox Homeostasis Scene... 320 Mitochondrial Redoxin Proteins and Other Thiolic Systems.......................... 323 Glutaredoxins ............................................................................................... 324 Thioredoxins ................................................................................................ 326 Peroxiredoxins.............................................................................................. 327 Glutathione................................................................................................... 329

Connection of Lipoamide with Glutathione via Glutaredoxin ........................ 330 Connection of Lipoamide with Thioredoxin ................................................... 336 Interaction of Lipoamide with Peroxiredoxin.................................................. 338 Concluding Remarks........................................................................................ 339 Abbreviations ................................................................................................... 340 References ........................................................................................................ 340

Lipoic acid in the form of enzyme-bound lipoamide plays an important role in the mitochondria as a thiol-disulfide redox couple that captures two energetic electrons produced during the highly exergonic decarboxylation of 2-oxoacids or glycine and transfers them to NADþ, thus contributing to the obtention of metabolically useful reducing power. The reduced form of this redox couple, dihydrolipoamide, is the strongest cellular thiol reductant (Eo0 ¼0.320 V).