THE FORMATION, RESOLUTION, AND OPTICAL PROPERTIES OF THE DIASTEREOISOMERIC SULFOXIDES DERIVED FROM l-METHIONINE

Lavine, Theodore F.

doi:10.1016/s0021-9258(17)30864-5

Cited by 101 publications

(20 citation statements)

References 9 publications

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“…116−119 Selenoxide can in turn be reduced back to SeMet by glutathione (GSH). 120−122 Met residues are oxidized to the sulfoxide by H 2 O 2 , 69,123 but GSH cannot reduce methionine sulfoxide (MetSO). 120,122 In the parent Tyr-less VVD-III construct, the remaining flavin-proximal Met residues (Met95, Met117, and Met179) were substituted individually with hydrophobic (Leu or Ile) or hydrophilic (Gln) residues.…”

Section: ■ Resultsmentioning

confidence: 99%

“…Photoreduction kinetics were recorded in the presence of varying concentrations of oxidants (H 2 O 2 ), reductants [glutathione (GSH) or ascorbate], and D 2 O. Note that the formal potential of SeMet ( E pa = 0.84 V vs NHE) is lower than that of Met ( E pa = 1.21 V vs NHE) and SeMet is readily oxidized to the selenoxide form by peroxide (H 2 O 2 ). − Selenoxide can in turn be reduced back to SeMet by glutathione (GSH). − Met residues are oxidized to the sulfoxide by H 2 O 2 , , but GSH cannot reduce methionine sulfoxide (MetSO). , In the parent Tyr-less VVD-III construct, the remaining flavin-proximal Met residues (Met95, Met117, and Met179) were substituted individually with hydrophobic (Leu or Ile) or hydrophilic (Gln) residues. Met95 and Met179 are conserved as Leu and Ile, respectively, in all phototropin LOV2 domains .…”

Section: Resultsmentioning

confidence: 99%

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Peripheral Methionine Residues Impact Flavin Photoreduction and Protonation in an Engineered LOV Domain Light Sensor

et al. 2021

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Proton-coupled electron transfer reactions play critical roles in many aspects of sensory phototransduction. In the case of flavoprotein light sensors, reductive quenching of flavin excited states initiates chemical and conformational changes that ultimately transmit light signals to downstream targets. These reactions generally require neighboring aromatic residues and proton-donating side chains for rapid and coordinated electron and proton transfer to flavin. Although photoreduction of flavoproteins can produce either the anionic (ASQ) or neutral semiquinone (NSQ), the factors that favor one over the other are not well understood. Here we employ a biologically active variant of the light-oxygen-voltage (LOV) domain protein VVD devoid of the adduct-forming Cys residue (VVD-III) to probe the mechanism of flavin photoreduction and protonation. A series of isosteric and conservative residue replacements studied by rate measurements, fluorescence quantum yields, FTIR difference spectroscopy, and molecular dynamics simulations indicate that tyrosine residues facilitate charge recombination reactions that limit sustained flavin reduction, whereas methionine residues facilitate radical propagation and quenching and also gate solvent access for flavin protonation. Replacement of a single surface Met residue with Leu favors formation of the ASQ over the NSQ and desensitizes photoreduction to oxidants. In contrast, increasing site hydrophilicity by Gln substitution promotes rapid NSQ formation and weakens the influence of the redox environment. Overall, the photoreactivity of VVD-III can be understood in terms of redundant electron donors, internal hole quenching, and coupled proton transfer reactions that all depend upon protein conformation, dynamics, and solvent penetration.

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Section: ■ Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Peripheral Methionine Residues Impact Flavin Photoreduction and Protonation in an Engineered LOV Domain Light Sensor

et al. 2021

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“…The monoclonal anti-His-tag antibody, racemic L-MetSO, and all other reagents and chemicals were of the highest quality commercially available from Sigma-Aldrich (Argentina) or similar. The separation of the L-MetSO isomers was carried out following the method of Lavine [34] from the pure L-MetSO racemic mixture by differential precipitation with picric acid and methanol. Under our conditions, we obtained a purity greater than 99% for the L-Met(S)SO isomer and a purity of 90% for the L-Met(R)SO isomer [the remaining 10% corresponds to the L-Met(S)SO isomer].…”

Section: Methodsmentioning

confidence: 99%

Functional characterization of methionine sulfoxide reductases from Leptospira interrogans

Sasoni

Hartman

Guerrero

et al. 2021

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics

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“…Methionine oxidation is a common reaction in proteins that plays important regulative and protective roles and can affect protein conformation. 47,48 Methionine sulfoxide is formed via a formal oxygen transfer by a two-electron oxidation in the presence of appropriate oxidants.…”

Section: Readily Oxidizable Methionines Contribute To Initial Degradationmentioning

confidence: 99%

Inactivation and Site-specific Oxidation of Aquatic Extracellular Bacterial Leucine Aminopeptidase by Singlet Oxygen

Egli

Stravs

Janssen

2020

Environ. Sci. Technol.

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Extracellular enzymes are master recyclers of organic matter and to predict their functional lifetime, we need to understand their environmental transformation processes. In surface waters, direct and indirect photochemical transformation is a known driver of inactivation. We investigated molecular changes that occur along with inactivation in aminopeptidase, an abundant class of extracellular enzymes. We studied the inactivation kinetics and localized oxidation caused by singlet oxygen, 1 O 2 , a major photochemically-derived oxidant towards amino acids. Aminopeptidase showed second order inactivation rate constants with 1 O 2 comparable to those of free amino acids. We then visualized site-specific oxidation kinetics within the three-dimensional protein and demonstrated that fastest oxidation occurred around the active site and at other reactive amino acids. However, second order oxidation rate constants did not correlate strictly with the 1 O 2 -accessible surface areas of those amino acids.We inspected site-specific processes by a comprehensive suspect screening for 723'288 possible transformation products. We concluded that histidine involved in zinc coordination at the active site reacted slower than expected by its accessibility and we differentiated between two competing reaction pathways of 1 O 2 with tryptophan residues. This systematic analysis can be directly applied to other proteins and transformation reactions.

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THE FORMATION, RESOLUTION, AND OPTICAL PROPERTIES OF THE DIASTEREOISOMERIC SULFOXIDES DERIVED FROM l-METHIONINE

Cited by 101 publications

References 9 publications

Peripheral Methionine Residues Impact Flavin Photoreduction and Protonation in an Engineered LOV Domain Light Sensor

Peripheral Methionine Residues Impact Flavin Photoreduction and Protonation in an Engineered LOV Domain Light Sensor

Functional characterization of methionine sulfoxide reductases from Leptospira interrogans

Inactivation and Site-specific Oxidation of Aquatic Extracellular Bacterial Leucine Aminopeptidase by Singlet Oxygen

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