Nitrosyl hemoglobin: EPR components at low temperatures

Wajnberg, Eliane; Linhares, Marília Paixão; El-Jaick, Léa Jaccoud; Bemski, G.

doi:10.1007/bf00195444

Cited by 23 publications

(4 citation statements)

References 30 publications

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“…To prepare (NO-ferroheme)4-Hb, solution of bovine Hb (10 ml PBS; 1 mmol l −1 in heme; pH 7.4; in a Thunberg tube) was first deoxygenated in a vacuum/N 2 gas system for 15 min, then reduced with sodium dithionite (1.5 mmol l −1 ), following another 5 min deoxygenation, then treated under slow agitation with pure NO gas (1 atm, 5 min) and further evacuated (5 min) to remove dissolved but unbound NO. EPR spectra of (NO-ferroheme)4-Hb were generally similar to previously reported 55 , and we observed the formation of both six-coordinated and five-coordinated NO-ferroheme species. We ascribe this preparation as being (NO-ferroheme)4-Hb.…”

Section: Methodssupporting

confidence: 89%

NO-ferroheme is a signaling entity in the vasculature

Kleschyov,

Zhuge,

Schiffer

et al. 2023

Nat Chem Biol

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Despite wide appreciation of the biological role of nitric oxide (NO) synthase (NOS) signaling, questions remain about the chemical nature of NOS-derived bioactivity. Here we show that NO-like bioactivity can be efficiently transduced by mobile NO-ferroheme species, which can transfer between proteins, partition into a hydrophobic phase and directly activate the sGC–cGMP–PKG pathway without intermediacy of free NO. The NO-ferroheme species (with or without a protein carrier) efficiently relax isolated blood vessels and induce hypotension in rodents, which is greatly potentiated after the blockade of NOS activity. While free NO-induced relaxations are abolished by an NO scavenger and in the presence of red blood cells or blood plasma, a model compound, NO-ferroheme-myoglobin preserves its vasoactivity suggesting the physiological relevance of NO-ferroheme species. We conclude that NO-ferroheme behaves as a signaling entity in the vasculature.

show abstract

Section: Methodssupporting

confidence: 89%

NO-ferroheme is a signaling entity in the vasculature

Kleschyov,

Zhuge,

Schiffer

et al. 2023

Nat Chem Biol

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show abstract

“…To prepare (NO-ferroheme)4-Hb, solution of bovine hemoglobin (10 mL PBS; 1 mmol/L in heme; pH 7.4) was first deoxygenated in a vacuum/N2 gas system for 15min, then reduced with sodium dithionite (1.5mmol/L), following another 15min deoxygenation, then treated under slow agitation with pure NO gas (1 atm, 5 min) and further evacuated (5 min) to remove dissolved but unbound NO. EPR spectra of NO-ferroheme-Hb were similar to previously reported 44 . NO-ferrohememyoglobin was prepared using similar protocol; in some preparations, sodium borohydride (1,5 mmol/L) was used as reducing agent instead of sodium dithionite; EPR spectra of both these NOferroheme-Mb preparations were identical to those described previously 45 (pH values of the solutions were about 6).…”

Section: Synthesis Of No-ferroheme Preparationssupporting

confidence: 88%

NO-ferroheme is a signaling entity in the vasculature

Zhuge

Schiffer

Guimarães

et al. 2023

Preprint

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Despite wide appreciation of the biological role of nitric oxide (NO) synthase (NOS) signaling, questions remain about the chemical nature of NOS-derived bioactivity. Here we show that NO-like bioactivity can be efficiently transduced by mobile NO-ferroheme species which can exchange proteins, partition to the hydrophobic phase, and directly activate the sGC-cGMP-PKG pathway without the intermediacy of free NO. The NO-ferroheme entity efficiently relaxes isolated blood vessels and induces hypotension in rodents, which is greatly potentiated after blockade of NOS activity. While free NO-induced relaxations are abolished by an NO scavenger and in the presence of red blood cells or blood plasma, NO-ferroheme preserves its vasoactivity, suggesting physiological relevance of these yet underappreciated species. We conclude that NO-ferroheme behaves as a signaling entity in the vasculature.

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“…This hypothesis is in agreement with the anomalous temperature dependence of the intensity of EPR spectra of these complexes which was attributed to the equilibrium between two different conformations (16), one of which is EPR silent.…”

Section: Resultssupporting

confidence: 74%