Catalytic generation of N2O3 by the concerted nitrite reductase and anhydrase activity of hemoglobin

Basu, Swati; Grubina, Rozalina; Huang, Jinming; Conradie, Jeanet; Huang, Zhi; Jeffers, Anne; Jiang, Alice; He, Xiaojun; Azarov, Ivan; Seibert, Ryan; Mehta, A. R.; Patel, Rakesh P.; King, S. Bruce; Hogg, Neil; Ghosh, Abhik; Gladwin, Mark T.; Kim‐Shapiro, Daniel B.

doi:10.1038/nchembio.2007.46

Cited by 212 publications

(329 citation statements)

References 47 publications

Supporting

Mentioning

303

Contrasting

Unclassified

Order By: Relevance

“…The five-coordinate heme can now bind to external ligands such as nitrite. As evidenced in recent reports (45,46) by experimental and density functional theoretical studies, nitrite may bind to the heme in either N-nitro-or O-nitrito-conformations (Scheme 1, second step). We cannot conclude from our results if either binding mode is preferred, and given the differences in the heme pocket of Ngb, as compared with Mb (supplemental Fig.…”

Section: Discussionmentioning

confidence: 99%

Human Neuroglobin Functions as a Redox-regulated Nitrite Reductase

Tiso

Tejero

Basu

et al. 2011

Journal of Biological Chemistry

Self Cite

255

323

View full text Add to dashboard Cite

Neuroglobin is a highly conserved hemoprotein of uncertain physiological function that evolved from a common ancestor to hemoglobin and myoglobin. It possesses a six-coordinate heme geometry with proximal and distal histidines directly bound to the heme iron, although coordination of the sixth ligand is reversible. We show that deoxygenated human neuroglobin reacts with nitrite to form nitric oxide (NO). This reaction is regulated by redox-sensitive surface thiols, cysteine 55 and 46, which regulate the fraction of the five-coordinated heme, nitrite binding, and NO formation. Replacement of the distal histidine by leucine or glutamine leads to a stable five-coordinated geometry; these neuroglobin mutants reduce nitrite to NO ϳ2000 times faster than the wild type, whereas mutation of either Cys-55 or Cys-46 to alanine stabilizes the six-coordinate structure and slows the reaction. Using lentivirus expression systems, we show that the nitrite reductase activity of neuroglobin inhibits cellular respiration via NO binding to cytochrome c oxidase and confirm that the six-to-five-coordinate status of neuroglobin regulates intracellular hypoxic NO-signaling pathways. These studies suggest that neuroglobin may function as a physiological oxidative stress sensor and a post-translationally redox-regulated nitrite reductase that generates NO under six-tofive-coordinate heme pocket control. We hypothesize that the sixcoordinate heme globin superfamily may subserve a function as primordial hypoxic and redox-regulated NO-signaling proteins.

show abstract

Section: Discussionmentioning

confidence: 99%

Human Neuroglobin Functions as a Redox-regulated Nitrite Reductase

Tiso

Tejero

Basu

et al. 2011

Journal of Biological Chemistry

Self Cite

255

323

View full text Add to dashboard Cite

show abstract

“…When AS was added to essentially the same concentration of Hb and almost 10 mM red cell encapsulated Hb (41% Hct), 67-69 μM metHb was made ( Figure 8A). Since nitrite bound metHb is EPR silent [102], there is actually probably slightly more metHb made in the case with RBCs present. The reaction of nitrite with oxyHb in the RBC may also contribute slightly to metHb formation.…”

Section: Discussionmentioning

confidence: 99%

“…NO reacts with oxyHb to form metHb and nitrate with a rate constant of 5-8 × 10 7 M −1 s −1 [25][26][27][28]. MetHb binds nitrite reversibly with a dissociation constant of 1 mM [98] or lower under certain conditions [102]. In our systems, peroxide formed by reaction 2 appears to be scavenged by catalase (reaction 4 where the initial step in this reaction occurs with a rate constant greater than 10 7 M −1 s −1 [95]).…”

Section: Acknowledgementsmentioning

confidence: 99%

The potential of Angeli's salt to decrease nitric oxide scavenging by plasma hemoglobin

Azarov

Jeffers

et al. 2008

Free Radical Biology and Medicine

Self Cite

View full text Add to dashboard Cite

Release of hemoglobin from the erythrocyte during intravascular hemolysis contributes to the pathology of a variety of diseased states. This effect is partially due to the enhanced ability of cellfree plasma hemoglobin, which is primarily found in the ferrous, oxygenated state, to scavenge nitric oxide. Oxidation of the cell-free hemoglobin to methemoglobin, which does not effectively scavenge nitric oxide, using inhaled nitric oxide has been shown to be effective in limiting pulmonary and systemic vasoconstriction. However, the ferric heme species may be reduced back to ferrous hemoglobin in plasma and has the potential to drive injurious redox chemistry. We propose that compounds that selectively convert cell-free hemoglobin to ferric, and ideally iron-nitrosylated heme species that do not actively scavenge nitric oxide would effectively treat intravascular hemolysis. We show here that nitroxyl, generated by Angeli's salt (Sodium α-oxyhyponitrite, Na 2 N 2 O 3 ), preferentially reacts with cell-free hemoglobin compared to that encapsulated in the red blood cell under physiologically relevant conditions. Nitroxyl oxidizes oxygenated ferrous hemoglobin to methemoglobin and can convert the methemoglobin to a more stable, less toxic species, iron-nitrosyl hemoglobin. These results support the notion that Angeli's salt or a similar compound could be used to effectively treat conditions associated with intravascular hemolysis.

show abstract

“…Although the importance of NO 2 Ϫ has received increasing appreciation (9) as being central to processes including exercise (10), hypoxic vasodilation (11), myocardial preconditioning (12, 13), and angiogenesis (14), controversy surrounds the chemistry, kinetics, and tissue specificity of NO 2 Ϫ bioactivity (15, 16). Perhaps the greatest uncertainty pertains to the role of heme moieties in NO 2 Ϫ metabolism (6,10,12,13,(15)(16)(17)(18)(19)(20)(21)(22). We therefore sought to address systematically the path of NO 2 Ϫ biotransformation in hypoxic tissues and its processing into NO and NO-related species across levels of biological organization by employing an experimental paradigm that ranges from cellular NO 2 Ϫ uptake in vitro to tissue NO 2 Ϫ utilization in vivo.…”

Section: Nitric Oxide (No)mentioning

confidence: 99%

Tissue Processing of Nitrite in Hypoxia

Feelisch

Fernandez

Bryan

et al. 2008

Journal of Biological Chemistry

194

View full text Add to dashboard Cite

Although nitrite (NO 2؊ ) and nitrate (NO 3 ؊ ) have been considered traditionally inert byproducts of nitric oxide (NO) metabolism, recent studies indicate that NO 2 ؊ represents an important source of NO for processes ranging from angiogenesis through hypoxic vasodilation to ischemic organ protection. Despite intense investigation, the mechanisms through which NO 2 ؊ exerts its physiological/pharmacological effects remain incompletely understood. We sought to systematically investigate the fate of NO 2 ؊ in hypoxia from cellular uptake in vitro to tissue utilization in vivo using the Wistar rat as a mammalian model. We find that most tissues (except erythrocytes) produce free NO at rates that are maximal under hypoxia and that correlate robustly with each tissue's capacity for mitochondrial oxygen consumption. By comparing the kinetics of NO release before and after ferricyanide addition in tissue homogenates to mathematical models of NO 2 ؊ reduction/NO scavenging, we show that the amount of nitrosylated products formed greatly exceeds what can be accounted for by NO trapping. This difference suggests that such products are formed directly from NO 2 ؊ , without passing through the intermediacy of free NO. Inhibitor and subcellular fractionation studies indicate that NO 2 ؊ reductase activity involves multiple redundant enzymatic systems (i.e. heme, iron-sulfur cluster, and molybdenumbased reductases) distributed throughout different cellular compartments and acting in concert to elicit NO signaling. These observations hint at conserved roles for the NO 2 ؊ -NO pool in cellular processes such as oxygen-sensing and oxygen-dependent modulation of intermediary metabolism. Nitric oxide (NO)3 is the archetypal effector of redox-regulated signal transduction throughout phylogeny, from microorganisms to plants and animals (1). The conserved influences of NO extend from the regulation of basic cellular processes such as intermediary metabolism (2), cellular proliferation (3), and apoptosis (4) to systemic processes such as hypoxic vasoregulation (5). Mammalian NO production has been attributed to the enzymatic activity of NO synthases, nitrate (NO 3 Ϫ )/nitrite (NO 2 Ϫ ) reductases and non-enzymatic NO 2 Ϫ reduction (6). The NO produced is believed to act directly as a signaling molecule by binding to the heme of soluble guanylyl cyclase or nitrosating peptide/protein cysteine residues (7). More recently, it has become apparent that NO 2 Ϫ , previously considered an inert byproduct of NO metabolism present in plasma (50 -500 nM) and tissues (0.5-25 M), is, under some conditions, also a source of NO/nitrosothiol signaling (6,8). Although the importance of NO 2 Ϫ has received increasing appreciation (9) as being central to processes including exercise (10), hypoxic vasodilation (11), myocardial preconditioning (12, 13), and angiogenesis (14), controversy surrounds the chemistry, kinetics, and tissue specificity of NO 2 Ϫ bioactivity (15, 16). Perhaps the greatest uncertainty pertains to the role of heme moieties in NO 2...

show abstract

Catalytic generation of N2O3 by the concerted nitrite reductase and anhydrase activity of hemoglobin

Cited by 212 publications

References 47 publications

Human Neuroglobin Functions as a Redox-regulated Nitrite Reductase

Human Neuroglobin Functions as a Redox-regulated Nitrite Reductase

The potential of Angeli's salt to decrease nitric oxide scavenging by plasma hemoglobin

Tissue Processing of Nitrite in Hypoxia

Contact Info

Product

Resources

About