Modulating the nitrite reductase activity of globins by varying the heme substituents: Utilizing myoglobin as a model system

Galinato, Mary Grace I.; Fogle, Robert S.; Stetz, Amanda; Galan, Jhenny F.

doi:10.1016/j.jinorgbio.2015.10.010

Cited by 6 publications

(4 citation statements)

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“…The typical spectra of metalloporphyrins (such as [Zn II (TPP)] and [Co III (TPP)Cl]) exhibit an intense Soret band at ∼420 nm and weaker Q bands at ∼550 nm. − In contrast, in the case of [Mn III (TPP)Cl]), the Soret band seems split into two less intense features, one of which is a prominent peak at lower energy (477 nm), and the other one is a very broad band that occurs at higher energy (around 375 nm). , Figure presents the absorption and low-temperature MCD spectra of [Mn III (TPP)Cl], which are resolved into 18 Gaussians by conducting a correlated fit of these data. In this section, the Roman numeral scheme is used to make reference to the main absorption bands (see Figure ).…”

Section: Results and Analysismentioning

confidence: 99%

Elucidating the Electronic Structure of High-Spin [Mn^III(TPP)Cl] Using Magnetic Circular Dichroism Spectroscopy

et al. 2020

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Manganese porphyrins are used as catalysts in the oxidation of olefins and nonactivated hydrocarbons. Key to these reactions are high-valent Mn−(di)oxo species, for which [Mn(Porph)(X)] serve as precursors. To elucidate their properties, it is crucial to understand the interaction of the Mn center with the porphyrin ligand. Our study focuses on simple high-spin [Mn III (TPP)X] (X = F, Cl, I, Br) complexes with emphasis on the spectroscopic properties of [Mn III (TPP)Cl], using variabletemperature variable-field magnetic circular dichroism spectroscopy and time-dependent density functional theory to help with band assignments. The optical properties of [Mn III (TPP)Cl] are complicated and unusual, with a Soret band showing a high-intensity feature at 21050 cm −1 and a broad band that spans 23200−31700 cm −1 . The 15000−18500 cm −1 region shows the Cl(p x/y ) → d π (CT (Cl,π) ), Q band, and overlap-forbidden Cl(p x/y )_d π → d x 2 −y 2 transitions that gain intensity from the strongly allowed π → π* (0) transition. The 20000−21000 cm −1 region displays the prominent pseudo A-type signal of the Soret band. The strongly absorbing features at 22500−28000 cm −1 exhibit A 1u ⟨79⟩/A 2u ⟨81⟩ → d π , CT (Cl,π/σ) , and symmetry-forbidden CT character, mixed with the π → π* (0) transition. The strong d x 2 −y 2 _B 1g ⟨80⟩ orbital interaction drives the ground-state MO mixing. Importantly, the splitting of the Soret band is explained by strong mixing of the porphyrin A 2u (π)⟨81⟩ and the Cl(p z )_d z 2 orbitals. Through this direct orbital pathway, the π → π* (0) transition acquires intrinsic metal-d → porphyrin CT character, where the π → π* (0) intensity is then transferred into the high-energy CT region of the optical spectrum. The heavier halide complexes support this conclusion and show enhanced orbital mixing and drastically increased Soret band splittings, where the 21050 cm −1 band shifts to lower energy and the high-energy features in the 23200−31700 cm −1 range increase further in intensity, compared to the chloro complex.

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Section: Results and Analysismentioning

confidence: 99%

Elucidating the Electronic Structure of High-Spin [Mn^III(TPP)Cl] Using Magnetic Circular Dichroism Spectroscopy

et al. 2020

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“…Moreover, Galinato et al [32] showed that the NIR activity of Mb is modulated by the substituent at heme 2,4-positions. In a recent study on a protein model of native CcO, L29H/F43H Mb, as designed by Lu and co-workers [33], we found that Cu(II) enhances whereas Zn(II) inhibits the protein NIR activity, which provides valuable insight into the role of copper in the Cu B site for native CcO with an additional function of NIR in biological system [34].…”

Section: Introductionmentioning

confidence: 99%

Regulating the nitrite reductase activity of myoglobin by redesigning the heme active center

Yuan

Gao

et al. 2016

Nitric Oxide

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Heme proteins perform diverse functions in living systems, of which nitrite reductase (NIR) activity receives much attention recently. In this study, to better understand the structural elements responsible for the NIR activity, we used myoglobin (Mb) as a model heme protein and redesigned the heme active center, by introducing one or two distal histidines, and by creating a channel to the heme center with removal of the native distal His64 gate (His to Ala mutation). UV-Vis kinetic studies, combined with EPR studies, showed that a single distal histidine with a suitable position to the heme iron, i.e., His43, is crucial for nitrite (NO2(-)) to nitric oxide (NO) reduction. Moreover, creation of a water channel to the heme center significantly enhanced the NIR activity compared to the corresponding mutant without the channel. In addition, X-ray crystallographic studies of F43H/H64A Mb and its complexes with NO2(-) or NO revealed a unique hydrogen-bonding network in the heme active center, as well as unique substrate and product binding models, providing valuable structural information for the enhanced NIR activity. These findings enriched our understanding of the structure and NIR activity relationship of heme proteins. The approach of creating a channel in this study is also useful for rational design of other functional heme proteins.

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“…Design of metalloenzymes by incorporation of heme analogs in apo-Mb:Heme b substitution of F33Y CuBMb with heme a analogs, and the correlation of heme redox potential and catalytic O2 reduction activity for the protein derivatives[133].To provide insight into the structure and NIR activity relationship of globins as regulated by heme 2-and 4-substitutions, Galinato et al[134] prepared several Mb variants containing DA-heme, heme, deuteroheme and mesoheme, respectively, with increasing of the electron releasing capacity of the -R groups at positions 2 and 4.…”

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“…Fine-tuning the NIR activity of Mb: (a) Correlation between the rate constants of nitrite reduction by reconstituted Mbs and the natural charge on the Fe center.Reprinted with permission from ref [134],. Copyright 2016 Elsevier; (b) Relative reactivities of Mb distal histidine mutants and the channel mutants with respect to that of WT Mb.…”

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Rational design of metalloenzymes: From single to multiple active sites

Lin

2017

Coordination Chemistry Reviews

137

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Artificial metalloenzymes combine the advantages of both natural enzymes and chemically synthesized models, which have achieved significant progress in the last decade. This review summarizes the recent achievements in rational design of metalloenzymes from single to multiple active sites in natural or de novo protein scaffolds, with a diverse range of functionalities, even beyond those of natural metalloenzymes. These achievements include construction of mononuclear active site by metal substitution or incorporation, design of homo-or hetero-dinuclear site, introduction of Fe-sulfur or other metal clusters, reconstitution of metallo-porphyrins or other metal complexes, and design of dual or multiple active sites in single, dimeric proteins, de novo proteins, protein-protein interfaces, as well as protein oligomers and polymers. Other new trends in recent designs are also discussed. The progress not only elucidates the structural and functional relationship of natural metalloenzymes, but also provides practical clues for design of advanced artificial metalloenzymes with potential applications.

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Modulating the nitrite reductase activity of globins by varying the heme substituents: Utilizing myoglobin as a model system

Cited by 6 publications

References 71 publications

Elucidating the Electronic Structure of High-Spin [Mn^III(TPP)Cl] Using Magnetic Circular Dichroism Spectroscopy

Elucidating the Electronic Structure of High-Spin [Mn^III(TPP)Cl] Using Magnetic Circular Dichroism Spectroscopy

Regulating the nitrite reductase activity of myoglobin by redesigning the heme active center

Rational design of metalloenzymes: From single to multiple active sites

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Modulating the nitrite reductase activity of globins by varying the heme substituents: Utilizing myoglobin as a model system

Cited by 6 publications

References 71 publications

Elucidating the Electronic Structure of High-Spin [MnIII(TPP)Cl] Using Magnetic Circular Dichroism Spectroscopy

Elucidating the Electronic Structure of High-Spin [MnIII(TPP)Cl] Using Magnetic Circular Dichroism Spectroscopy

Regulating the nitrite reductase activity of myoglobin by redesigning the heme active center

Rational design of metalloenzymes: From single to multiple active sites

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Elucidating the Electronic Structure of High-Spin [Mn^III(TPP)Cl] Using Magnetic Circular Dichroism Spectroscopy

Elucidating the Electronic Structure of High-Spin [Mn^III(TPP)Cl] Using Magnetic Circular Dichroism Spectroscopy