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Role of the general base Glu-268 in nitroglycerin bioactivation and superoxide formation by aldehyde dehydrogenase-2.
J Biol Chem. 2009 Jul 24; 284(30):19878-86.JB

Abstract

Mitochondrial aldehyde dehydrogenase-2 (ALDH2) plays an essential role in nitroglycerin (GTN) bioactivation, resulting in formation of NO or a related activator of soluble guanylate cyclase. ALDH2 denitrates GTN to 1,2-glyceryl dinitrate and nitrite but also catalyzes reduction of GTN to NO. To elucidate the relationship between ALDH2-catalyzed GTN bioconversion and established ALDH2 activities (dehydrogenase, esterase), we compared the function of the wild type (WT) enzyme with mutants lacking either the reactive Cys-302 (C302S) or the general base Glu-268 (E268Q). Although the C302S mutation led to >90% loss of all enzyme activities, the E268Q mutant exhibited virtually unaffected rates of GTN denitration despite low dehydrogenase and esterase activities. The nucleotide co-factor NAD caused a pronounced increase in the rates of 1,2-glyceryl dinitrate formation by WT-ALDH2 but inhibited the reaction catalyzed by the E268Q mutant. GTN bioactivation measured as activation of purified soluble guanylate cyclase or release of NO in the presence of WT- or E268Q-ALDH2 was markedly potentiated by superoxide dismutase, suggesting that bioavailability of GTN-derived NO is limited by co-generation of superoxide. Formation of superoxide was confirmed by determination of hydroethidine oxidation that was inhibited by superoxide dismutase and the ALDH2 inhibitor chloral hydrate. E268Q-ALDH2 exhibited approximately 50% lower rates of superoxide formation than the WT enzyme. Our results suggest that Glu-268 is involved in the structural organization of the NAD-binding pocket but is not required for GTN denitration. ALDH2-catalyzed superoxide formation may essentially contribute to oxidative stress in GTN-exposed blood vessels.

Authors+Show Affiliations

Department of Pharmacology and Toxicology, Karl-Franzens-Universität Graz, A-8010 Graz, Austria.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19506075

Citation

Wenzl, M Verena, et al. "Role of the General Base Glu-268 in Nitroglycerin Bioactivation and Superoxide Formation By Aldehyde Dehydrogenase-2." The Journal of Biological Chemistry, vol. 284, no. 30, 2009, pp. 19878-86.
Wenzl MV, Beretta M, Gorren AC, et al. Role of the general base Glu-268 in nitroglycerin bioactivation and superoxide formation by aldehyde dehydrogenase-2. J Biol Chem. 2009;284(30):19878-86.
Wenzl, M. V., Beretta, M., Gorren, A. C., Zeller, A., Baral, P. K., Gruber, K., Russwurm, M., Koesling, D., Schmidt, K., & Mayer, B. (2009). Role of the general base Glu-268 in nitroglycerin bioactivation and superoxide formation by aldehyde dehydrogenase-2. The Journal of Biological Chemistry, 284(30), 19878-86. https://doi.org/10.1074/jbc.M109.005652
Wenzl MV, et al. Role of the General Base Glu-268 in Nitroglycerin Bioactivation and Superoxide Formation By Aldehyde Dehydrogenase-2. J Biol Chem. 2009 Jul 24;284(30):19878-86. PubMed PMID: 19506075.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Role of the general base Glu-268 in nitroglycerin bioactivation and superoxide formation by aldehyde dehydrogenase-2. AU - Wenzl,M Verena, AU - Beretta,Matteo, AU - Gorren,Antonius C F, AU - Zeller,Andreas, AU - Baral,Pravas K, AU - Gruber,Karl, AU - Russwurm,Michael, AU - Koesling,Doris, AU - Schmidt,Kurt, AU - Mayer,Bernd, Y1 - 2009/06/08/ PY - 2009/6/10/entrez PY - 2009/6/10/pubmed PY - 2009/9/29/medline SP - 19878 EP - 86 JF - The Journal of biological chemistry JO - J Biol Chem VL - 284 IS - 30 N2 - Mitochondrial aldehyde dehydrogenase-2 (ALDH2) plays an essential role in nitroglycerin (GTN) bioactivation, resulting in formation of NO or a related activator of soluble guanylate cyclase. ALDH2 denitrates GTN to 1,2-glyceryl dinitrate and nitrite but also catalyzes reduction of GTN to NO. To elucidate the relationship between ALDH2-catalyzed GTN bioconversion and established ALDH2 activities (dehydrogenase, esterase), we compared the function of the wild type (WT) enzyme with mutants lacking either the reactive Cys-302 (C302S) or the general base Glu-268 (E268Q). Although the C302S mutation led to >90% loss of all enzyme activities, the E268Q mutant exhibited virtually unaffected rates of GTN denitration despite low dehydrogenase and esterase activities. The nucleotide co-factor NAD caused a pronounced increase in the rates of 1,2-glyceryl dinitrate formation by WT-ALDH2 but inhibited the reaction catalyzed by the E268Q mutant. GTN bioactivation measured as activation of purified soluble guanylate cyclase or release of NO in the presence of WT- or E268Q-ALDH2 was markedly potentiated by superoxide dismutase, suggesting that bioavailability of GTN-derived NO is limited by co-generation of superoxide. Formation of superoxide was confirmed by determination of hydroethidine oxidation that was inhibited by superoxide dismutase and the ALDH2 inhibitor chloral hydrate. E268Q-ALDH2 exhibited approximately 50% lower rates of superoxide formation than the WT enzyme. Our results suggest that Glu-268 is involved in the structural organization of the NAD-binding pocket but is not required for GTN denitration. ALDH2-catalyzed superoxide formation may essentially contribute to oxidative stress in GTN-exposed blood vessels. SN - 0021-9258 UR - https://www.unboundmedicine.com/medline/citation/19506075/Role_of_the_general_base_Glu_268_in_nitroglycerin_bioactivation_and_superoxide_formation_by_aldehyde_dehydrogenase_2_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0021-9258(17)49271-4 DB - PRIME DP - Unbound Medicine ER -