Cyanide binding to ferrous and ferric microperoxidase-11

Ascenzi, Paolo; Sbardella, Diego; Santucci, Roberto; Coletta, Massimo

doi:10.1007/s00775-016-1361-z

Cited by 8 publications

(9 citation statements)

References 49 publications

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“…An associative character has been envisioned in the studies of the binding of cysteine/cysteinate 69 or hydrogen cyanide/cyanide toward microperoxidase peptides. 29,70 Furthermore, while the cysteine/cysteinate and hydrogen cyanide/ cyanide pairs have only one effectively binding species (namely, cysteinate and cyanide), both H 2 S and HS − can bind ferric heme compounds.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…This is further supported by the absence of distal mechanisms of stabilization of the water molecule in the NAcMP 11 -Fe III , favoring associative processes as compared to the Mb-Fe III . An associative character has been envisioned in the studies of the binding of cysteine/cysteinate or hydrogen cyanide/cyanide toward microperoxidase peptides. , Furthermore, while the cysteine/cysteinate and hydrogen cyanide/cyanide pairs have only one effectively binding species (namely, cysteinate and cyanide), both H 2 S and HS – can bind ferric heme compounds.…”

Section: Resultsmentioning

confidence: 99%

“…3,12,27,28 Nevertheless, the protonation states of the reactive species of sulfide have been tentatively assumed in different hemeproteins. Differing from the case of cyanide species HCN/CN − where only the deprotonated species is active for coordination to ferric heme compounds, 29,30 both the neutral and monoanionic forms of sulfide have been regarded as potential species participating in mechanistic proposals under biorelevant conditions. 5,6,8,31 Studies with picket-fence ferric porphyrinates in organic media, using gaseous H 2 S or NBu 4 SH as sources of the neutral and monoprotonated species, revealed that H 2 S did not bind to the ferric compounds.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The final product of the process, Fe III –S(sulfide) bond formation, has been assessed by resonance Raman and EPR in many examples, but the protonation could not be elucidated by these techniques. ,,, Nevertheless, the protonation states of the reactive species of sulfide have been tentatively assumed in different hemeproteins. Differing from the case of cyanide species HCN/CN – where only the deprotonated species is active for coordination to ferric heme compounds, , both the neutral and monoanionic forms of sulfide have been regarded as potential species participating in mechanistic proposals under biorelevant conditions. ,,, Studies with picket-fence ferric porphyrinates in organic media, using gaseous H 2 S or NBu 4 SH as sources of the neutral and monoprotonated species, revealed that H 2 S did not bind to the ferric compounds. The hydrosulfide, instead reduced the ferric porphyrinates and eventually bound to the ferrous forms …”

Section: Introductionmentioning

confidence: 99%

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Mechanism of Sulfide Binding by Ferric Hemeproteins

et al. 2018

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The reaction of hydrogen sulfide (HS) with hemeproteins is a key physiological reaction; still, its mechanism and implications are not completely understood. In this work, we propose a combination of experimental and theoretical tools to shed light on the reaction in model system microperoxidase 11 (MP11-Fe) and myoglobin (Mb-Fe), from the estimation of the intrinsic binding constants of the species HS and hydrosulfide (HS), and the computational description of the overall binding process. Our results show that HS and HS are the main reactive species in Mb-Fe and MP11-Fe, respectively, and that the magnitude of their intrinsic binding constants are similar to most of the binding constants reported so far for hemeproteins systems and model compounds. However, while the binding of HS to Mb-Fe was negligible, the binding of HS to MP11-Fe was significant, providing a frame for a discriminated analysis of both species and revealing differential mechanistic aspects. A joint inspection of the kinetic data and the free energy profiles of the binding processes suggests that a dissociative mechanism with the release of a coordinated water molecule as rate limiting step is operative in the binding of HS to Mb-Fe and that the binding of HS is prevented in the access to the protein matrix. For the MP11-Fe case, where no access restrictions for the ligands are present, an associative component in the mechanism seems to be operative. Overall, the results suggest that if accessing the active site then both HS and HS are capable of binding a ferric heme moiety.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanism of Sulfide Binding by Ferric Hemeproteins

et al. 2018

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“…This feature allows assessment of the impact of amino acid residues located on the proximal side of the heme ring on the studied reaction mechanism. MP-11 has been employed in numerous studies devoted to the development of heterogeneous biocatalysts/bioelectrocatalysts and spectroelectrochemical and bioelectronic sensors and devices. − Furthermore, MPs were the subject of intensive studies on their pH-dependent behavior in aqueous solution, − reactivity in catalytic oxidation of various substrates, − and substitution reactions with various ligands. − However, there are only a few reports available in the literature regarding the pH-dependent reactivity of MPs under alkaline conditions, where successive ionizations of H 2 O and HisH ligands result in the accumulation of [Fe III (OH)(HisH)] and [Fe III (OH)(His – )] species, respectively. , …”

Section: Introductionmentioning

confidence: 99%

Experimental and Computational Insight into the Mechanism of NO Binding to Ferric Microperoxidase. The Likely Role of Tautomerization to Account for the pH Dependence

et al. 2021

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According to the current paradigm, the metal− hydroxo bond in a six-coordinate porphyrin complex is believed to be significantly less reactive in ligand substitution than the analogous metal−aqua bond, due to a much higher strength of the former bond. Here, we report kinetic studies for nitric oxide (NO) binding to a heme-protein model, acetylated microperoxidase-11 (AcMP-11), that challenge this paradigm. In the studied pH range 7.4−12.6, ferric AcMP-11 exists in three acid− base forms, assigned in the literature as 2), and [(AcMP-11)Fe III (OH)(His − )] (3). From the pH dependence of the second-order rate constant for NO binding (k on ), we determined individual rate constants characterizing forms 1−3, revealing only a ca. 10-fold decrease in the NO binding rate on going from 1 (k on(1) = 3.8 × 10 6 M −1 s −1 ) to 2 (k on (2) = 4.0 × 10 5 M −1 s −1 ) and the inertness of 3. These findings lead to the abandonment of the dissociatively activated mechanism, in which the reaction rate can be directly correlated with the Fe−OH bond energy, as the mechanistic explanation for the process with regard to 2. The reactivity of 2 is accounted for through the existence of a tautomeric equilibrium between the major [(AcMP-11)Fe III (OH)(HisH)] (2a) and minor [(AcMP-11)Fe III (H 2 O)(His − )] (2b) species, of which the second one is assigned as the NO binding target due to its labile Fe−OH 2 bond. The proposed mechanism is further substantiated by quantum-chemical calculations, which confirmed both the significant labilization of the Fe−OH 2 bond in the [(AcMP-11)Fe III (H 2 O)(His − )] tautomer and the feasibility of the tautomer formation, especially after introducing empirical corrections to the computed relative acidities of the H 2 O and HisH ligands based on the experimental pK a values. It is shown that the "effective lability" of the axial ligand (OH − /H 2 O) in 2 may be comparable to the lability of the H 2 O ligand in 1.

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A Personal Account on Inorganic Reaction Mechanisms

Polaczek,

Kieca,

Oszajca

et al. 2023

The Chemical Record

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The presented Review is focused on the latest research in the field of inorganic chemistry performed by the van Eldik group and his collaborators. The first part of the manuscript concentrates on the interaction of nitric oxide and its derivatives with biologically important compounds. We summarized mechanistic information on the interaction between model porphyrin systems (microperoxidase) and NO as well as the recent studies on the formation of nitrosylcobalamin (CblNO). The following sections cover the characterization of the Ru(II)/Ru(III) mixed‐valence ion‐pair complexes, including Ru(II)/Ru(III)(edta) complexes. The last part concerns the latest mechanistic information on the DFT techniques applications. Each section presents the most important results with the mechanistic interpretations.

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Cyanide binding to ferrous and ferric microperoxidase-11

Cited by 8 publications

References 49 publications

Mechanism of Sulfide Binding by Ferric Hemeproteins

Mechanism of Sulfide Binding by Ferric Hemeproteins

Experimental and Computational Insight into the Mechanism of NO Binding to Ferric Microperoxidase. The Likely Role of Tautomerization to Account for the pH Dependence

A Personal Account on Inorganic Reaction Mechanisms

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