Sulfmyoglobin derived from deuterohemin reconstituted protein. 1. Structure of the initial complex based on the mechanism of formation of subsequent reaction products

Scharberg, Maureen A.; Mar, Gerd N. La

doi:10.1021/ja00068a007

Cited by 8 publications

(5 citation statements)

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“…15,26,27 It is then expected that the 2,4-protons of Co(III) deuteroheme (Figure 1), isoelectronic with Fe(II) deuteroheme, will also appear in a similar region if it were high-spin (S = 2). 15,26,27 However, none of the paramagnetic proton NMR signal are found in Figure S2 in SI. The NMR result excludes the high-spin state, and confirms the diamagnetic lowspin (S = 0) assignment for aquomet Co(III) Mb.…”

Section: ■ Discussionmentioning

confidence: 99%

“…In contrast, proton NMR discriminates the two states. For instance, in the NMR spectra of Fe(II) Mb, which is high-spin with S = 2, heme peripheral protons appear in the 50–60 ppm region because the 3d x 2 – y 2 orbital in Fe(II) are populated in the high-spin state. ,, It is then expected that the 2,4-protons of Co(III) deuteroheme (Figure ), isoelectronic with Fe(II) deuteroheme, will also appear in a similar region if it were high-spin ( S = 2). ,, However, none of the paramagnetic proton NMR signal are found in Figure S2 in SI. The NMR result excludes the high-spin state, and confirms the diamagnetic low-spin ( S = 0) assignment for aquomet Co(III) Mb.…”

Section: Discussionmentioning

confidence: 99%

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Relaxation Analysis of Ligand Binding to the Myoglobin Reconstituted with Cobaltic Heme

et al. 2013

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Myoglobin reconstituted with oxidized Co(III) deuteroheme was found to exhibit relatively large affinities to CN(-), N3(-), SCN(-), pyridine, and imidazole contrary to the early proposal. The ligand-induced changes in electronic spectra were less obvious than those of Fe(III) myoglobin owing to the absence of accompanied spin-state transition on the ligand binding. The relaxation kinetic analysis revealed that the ligand association rates were small and that the dissociation rates were still much smaller. The relatively large ligand affinities in Co(III) myoglobin were found due to the compensation of small association rates with fairly smaller dissociation rates. This is in marked contrast with the ligation profile in Fe(III) myoglobin where large association rates and small dissociation rates are generally observed. The rationale for the characteristic ligand-binding behavior of Co(III) myoglobin was provided on the basis of the properties of Co(III) which has an additional negative charge and forms stronger metal-ligand bonds than Fe(III).

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Section: ■ Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Relaxation Analysis of Ligand Binding to the Myoglobin Reconstituted with Cobaltic Heme

et al. 2013

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“…In general, the NMR spectra of all isomers showed symmetry reduction of the prosthetic group and alteration of the π conjugation of pyrrole B [34]. The sulfMbA structure is an episulfide across the β-β bond, which is rapidly reconverted to the protoheme when the heme is extracted from the protein [28, 34, 50, 51]. SulfMbB is characterized by a “ring opened episulfide” [34], while sulfMbC is described as a thiochlorin structure.…”

Section: Interaction Of H2s With Myoglobin and Hemoglobinmentioning

confidence: 99%

Hydrogen sulfide activation in hemeproteins: The sulfheme scenario

Ríos-González¹,

Román-Morales²,

Pietri³

et al. 2014

Journal of Inorganic Biochemistry

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Traditionally known as a toxic gas, hydrogen sulfide (H2S) is now recognized as an important biological molecule involved in numerous physiological functions. Like nitric oxide (•NO) and carbon monoxide (CO), H2S is produced endogenously in tissues and cells and can modulate biological processes by acting on target proteins. For example, interaction of H2S with the oxygenated form of human hemoglobin and myoglobin produces a sulfheme protein complex that has been implicated in H2S degradation. The presence of this sulfheme derivative has also been used as a marker for endogenous H2S synthesis and metabolism. Remarkably, human catalases and peroxidases also generate this sulfheme product. In this review, we describe the structural and functional aspects of the sulfheme derivative in these proteins and postulate a generalized mechanism for sulfheme protein formation. We also evaluate the possible physiological function of this complex and highlight the issues that remain to be assessed to determine the role of sulheme proteins in H2S metabolism, detection and physiology.

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“…The NMR spectra of all isomers showed symmetry reduction of the prosthetic group and alteration of the π conjugation of pyrrole B . The S A structure is an episulfide formed across the C3–C4 double bond (Figure ), which is rapidly reconverted to the protoheme when the heme is extracted from the protein, whereas S B is characterized as a “ring-opened episulfide”, and finally, S C is the thiochlorin structure. ,,, S A Mb (the S A form of Mb) is converted into both S B Mb and S C Mb, although conversion from S B Mb to S C Mb has not been observed, indicating that S A Mb could be the precursor of both sulfheme derivatives. , S C Mb is the most stable isomeric form when a vinyl group is bonded to C4 (Figure ) and appears to predominate under physiological conditions, implying that this compound may account for the reduced O 2 affinity in sulfMb. , …”

Section: Introductionmentioning

confidence: 99%

Homolytic Cleavage of Both Heme-Bound Hydrogen Peroxide and Hydrogen Sulfide Leads to the Formation of Sulfheme

et al. 2016

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Many heme-containing proteins with a histidine in the distal E7 (HisE7) position can form sulfheme in the presence of hydrogen sulfide (H2S) and a reactive oxygen species such as hydrogen peroxide. For reasons unknown, sulfheme derivatives are formed specifically on solvent-excluded heme pyrrole B. Sulfhemes severely decrease the oxygen-binding affinity in hemoglobin (Hb) and myoglobin (Mb). Here, use of hybrid quantum mechanical/molecular mechanical methods has permitted characterization of the entire process of sulfheme formation in the HisE7 mutant of hemoglobin I (HbI) from Lucina pectinata. This process includes a mechanism for H2S to enter the solvent-excluded active site through a hydrophobic channel to ultimately form a hydrogen bond with H2O2 bound to Fe(III). Proton transfer from H2O2 to His64 to form compound (Cpd) 0, followed by hydrogen transfer from H2S to the Fe(III)-H2O2 complex, results in homolytic cleavage of the O-O and S-H bonds to form a reactive thiyl radical (HS(•)), ferryl heme Cpd II, and a water molecule. Subsequently, the addition of HS(•) to Cpd II, followed by three proton transfer reactions, results in the formation of a three-membered ring ferric sulfheme that avoids migration of the radical to the protein matrix, in contrast to that in other peroxidative reactions. The transformation of this three-membered episulfide ring structure to the five-membered thiochlorin ring structure occurs through a significant potential energy barrier, although both structures are nearly isoenergetic. Both three- and five-membered ring structures reveal longer NB-Fe(III) bonds compared with other pyrrole nitrogen-Fe(III) bonds, which would lead to decreased oxygen binding. Overall, these results are in agreement with a wide range of experimental data and provide fertile ground for further investigations of sulfheme formation in other heme proteins and additional effects of H2S on cell signaling and reactivity.

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Sulfmyoglobin derived from deuterohemin reconstituted protein. 1. Structure of the initial complex based on the mechanism of formation of subsequent reaction products

Cited by 8 publications

References 0 publications

Relaxation Analysis of Ligand Binding to the Myoglobin Reconstituted with Cobaltic Heme

Relaxation Analysis of Ligand Binding to the Myoglobin Reconstituted with Cobaltic Heme

Hydrogen sulfide activation in hemeproteins: The sulfheme scenario

Homolytic Cleavage of Both Heme-Bound Hydrogen Peroxide and Hydrogen Sulfide Leads to the Formation of Sulfheme

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