scholarly journals Covalent heme attachment inSynechocystishemoglobin is required to prevent ferrous heme dissociation

2007 ◽  
Vol 16 (2) ◽  
pp. 250-260 ◽  
Author(s):  
Julie A. Hoy ◽  
Benoit J. Smagghe ◽  
Puspita Halder ◽  
Mark S. Hargrove
Keyword(s):  
Covalent Heme Attachment ◽  
Ferrous Heme

IR Signature of NO Binding to a Ferrous Heme Center

2013 ◽  
Vol 4 (15) ◽  
pp. 2414-2417 ◽  
Author(s):  
Francesco Lanucara ◽  
Debora Scuderi ◽  
Barbara Chiavarino ◽  
Simonetta Fornarini ◽  
Philippe Maitre ◽  
...  
Keyword(s):  
Ir Signature ◽  
Ferrous Heme

Electronic structure of nitrosyl ferrous heme complexes

1989 ◽  
Vol 111 (8) ◽  
pp. 2767-2772 ◽  
Author(s):  
Ahmad Waleh ◽  
Nan Ho ◽  
Lek Chantranupong ◽  
Gilda H. Loew
Keyword(s):  
Electronic Structure ◽  
Ferrous Heme

scholarly journals Heme oxygenase-2 (HO-2) binds and buffers labile heme, which is largely oxidized, in human embryonic kidney cells

2021 ◽  
Author(s):  
David A Hanna ◽  
Courtney M Moore ◽  
Liu Liu ◽  
Xiaojing Yuan ◽  
Angela S Fleischhacker ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Physiological Function ◽  
Hek293 Cells ◽  
Kidney Cells ◽  
Human Embryonic Kidney ◽  
Human Embryonic Kidney Cells ◽  
Heme Oxygenases ◽  
Heme Trafficking ◽  
Ferrous Heme

Heme oxygenases (HO) detoxify heme by oxidatively degrading it into carbon monoxide, iron, and biliverdin, which is reduced to bilirubin and excreted. Humans express two isoforms: inducible HO-1, which is up-regulated in response to various stressors, including excess heme, and constitutive HO-2. While much is known about the regulation and physiological function of HO-1, comparatively little is known about the role of HO-2 in regulating heme homeostasis. The biochemical necessity for expressing constitutive HO-2 is largely dependent on whether heme is sufficiently abundant and accessible as a substrate under conditions in which HO-1 is not induced. By measuring labile heme, total heme, and bilirubin in human embryonic kidney HEK293 cells with silenced or over-expressed HO-2, and various HO-2 mutant alleles, we found that endogenous heme is too limiting to support HO-2 catalyzed heme degradation. Rather, we discovered that a novel role for HO-2 is to bind and buffer labile heme. Taken together, in the absence of excess heme, we propose that HO-2 regulates heme homeostasis by acting as a heme buffering factor in control of heme bioavailability. When heme is in excess, HO-1 is induced and both HO-2 and HO-1 can provide protection from heme toxicity by enzymatically degrading it. Our results explain why catalytically inactive mutants of HO-2 are cytoprotective against oxidative stress. Moreover, the change in bioavailable heme due to HO-2 overexpression, which selectively binds ferric over ferrous heme, is consistent with the labile heme pool being oxidized, thereby providing new insights into heme trafficking and signaling.

The structure of a ferrous heme-nitro species in the binuclear heme a3/CuB center of ba3-cytochrome c oxidase as determined by resonance Raman spectroscopy

2015 ◽  
Vol 51 (2) ◽  
pp. 286-289 ◽  
Author(s):  
Andreas Loullis ◽  
Mohamed Radzi Noor ◽  
Tewfik Soulimane ◽  
Eftychia Pinakoulaki
Keyword(s):  
Raman Spectroscopy ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Resonance Raman Spectroscopy ◽  
Resonance Raman ◽  
Copper Center ◽  
Ferrous Heme

We present resonance Raman evidence for the formation of a ferrous heme-nitro species in the binuclear heme/copper center of ba3-oxidase.

Ascorbic Acid Catalyzes Nitric Oxide Production from Nitrite Ions.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1574-1574 ◽  
Author(s):  
Nathawut Sibmooh ◽  
Barbora Piknova ◽  
Alan N. Schechter
Keyword(s):  
Nitric Oxide ◽  
Ascorbic Acid ◽  
Rate Constant ◽  
Dehydroascorbic Acid ◽  
Nitrite Reduction ◽  
Erythrocyte Membranes ◽  
No Production ◽  
Ferrous Ions ◽  
Physiological Conditions ◽  
Ferrous Heme

Abstract We have previously shown that nitrite ions can be reduced by hemoglobin to nitric oxide (NO), a ubiquitous signaling molecule and potent vasodilator. Nitrite serves as a stable tissue and vascular source for NO production; the reduction reaction is maximal at about 50% oxygen saturation values and is enhanced at low pH but little is known about other effectors of this reaction. In the current work, we studied the effect of ascorbic acid on nitrite reduction under physiological conditions using chemiluminescence to quantify NO production. In physiological buffer, this reaction has a rate constant of about 1×10−5 M−1.s−1. Thus, a significant production of NO would likely occur in plasma only at pharmacological levels of ascorbic acid (> 1 mM) although lowering pH below 7.0 markedly enhances this reaction. Loading human erythrocytes with 0.5 mM dehydroascorbic acid, which is in redox equilibrium with ascorbic acid and which can significantly raise intracellular ascorbic acid levels, increased basal levels of nitrite ions from 42±9.0 nM to 98±56 nM. Uptake of nitrite ions into erythrocytes by incubation in 10 μM nitrite was increased about 1.5 fold by dehydroascorbic acid and the half-time of nitrite loss was slowed to the same extent. Ascorbic acid also reduced free ferric heme in erythrocytes and plasma to ferrous heme which catalyzed the reduction of nitrite to NO with a rate constant of 2.3×103 M−1.s−1 under physiological conditions. However, free ferrous ions did not significantly produce NO in physiological buffer (rate constant = 1.8×10−2 M−1.s−1). The reaction of ferrous heme with nitrite was not affected by heme binding to proteins such as hemopexin and albumin, or erythrocyte membranes. These results suggest that physiological levels of ascorbic acid (20–80 μM in plasma and erythrocytes) may act to catalyze NO production in the blood by promoting the reduction of nitrite ions by free ferrous heme and by increasing intra-erythrocytic levels of nitrite ions which can be reduced to NO by deoxyhemoglobin.

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