Alpha-lipoic acid supplementation protects enzymes from damage by nitrosative and oxidative stress

Authors

• Sylvia Hiller, University of North Carolina at Chapel Hill
• Robert DeKroon, University of North Carolina at Chapel Hill
• Eric D. Hamlett, Medical University of South Carolina
• Longquan Xu, University of North Carolina at Chapel Hill
• Cristina Osorio, University of North Carolina at Chapel Hill
• Jennifer Robinette, University of North Carolina at Chapel Hill
• Witold Winnik, U.S. Environmental Protection Agency
• Stephen Simington, University of North Carolina at Chapel Hill
• Nobuyo Maeda, University of North Carolina at Chapel Hill
• Oscar Alzate, Texas A&M Health Science CenterFollow
• Xianwen Yi, University of North Carolina at Chapel HillFollow

Document Type

Article

Date of this Version

2016

Citation

Biochimica et Biophysica Acta 1860 (2016), pp. 36–45, http://dx.doi.org/10.1016/j.bbagen.2015.09.001.

Comments

U.S. government work.

Abstract

Background: S-nitrosylation of mitochondrial enzymes involved in energy transfer under nitrosative stress may result in ATP deficiency. We investigated whether α-lipoic acid, a powerful antioxidant, could alleviate nitrosative stress by regulating S-nitrosylation,which could result in retaining themitochondrial enzyme activity.

Methods: In this study, we have identified the S-nitrosylated forms of subunit 1 of dihydrolipoyllysine succinyltransferase (complex III), and subunit 2 of the α-ketoglutarate dehydrogenase complex by implementing a fluorescence-based differential quantitative proteomics method.

Results: We found that the activities of these two mitochondrial enzymes were partially but reversibly inhibited by S-nitrosylation in cultured endothelial cells, and that their activities were partially restored by supplementation of α-lipoic acid. We show that protein S-nitrosylation affects the activity of mitochondrial enzymes that are central to energy supply, and that α-lipoic acid protectsmitochondrial enzymes by altering S-nitrosylation levels.

Conclusions: Inhibiting protein S-nitrosylation with α-lipoic acid seems to be a protective mechanism against nitrosative stress.

General significance: Identification and characterization of these new protein targets should contribute to expanding the therapeutic power of α-lipoic acid and to a better understanding of the underlying antioxidant mechanisms.