Studies on spin-trapped radicals in .gamma.-irradiated aqueous solutions of DL-methionine by high performance liquid chromatography and ESR spectroscopy

Makino, Keisuke

doi:10.1021/j100482a020

Cited by 29 publications

(15 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The observation of two intermediates in the auto-reduction of bis -Fe(IV) MauG by UV-Vis spectroscopy makes MauG a promising candidate for the characterization or capture of a methionine radical in a protein. Previously characterized methionine radicals were generated photochemically with free amino acids, leaving an open question as to how a protein environment might affect a methionine radical [26, 33]. We sought to characterize or capture any possible radical species formed during the return of bis -Fe(IV) MauG to the resting state.…”

Section: Discussionmentioning

confidence: 99%

Radical Trapping Study of the Relaxation of bis-Fe(IV) MauG

Davis

Koto

Liu

2018

ROS

View full text Add to dashboard Cite

The di-heme enzyme, MauG, utilizes a high-valent, charge-resonance stabilized bis-Fe(IV) state to perform protein radical-based catalytic chemistry. Though the bis-Fe(IV) species is able to oxidize remote tryptophan residues on its substrate protein, it does not rapidly oxidize its own residues in the absence of substrate. The slow return of bis-Fe(IV) MauG to its resting di-ferric state occurs via up to two intermediates, one of which has been previously proposed by Ma et al. (Biochem J 2016; 473:1769) to be a methionine-based radical in a recent study. In this work, we pursue intermediates involved in the return of high-valent MauG to its resting state in the absence of the substrate by EPR spectroscopy and radical trapping. The bis-Fe(IV) MauG is shown by EPR, HPLC, UV-Vis, and high-resolution mass spectrometry to oxidize the trapping agent, 5,5-dimethyl-1-pyrroline N-oxide (DMPO) to a radical species directly. Nitrosobenzene was also employed as a trapping agent and was shown to form an adduct with high-valent MauG species. The effects of DMPO and nitrosobenzene on the kinetics of the return to di-ferric MauG were both investigated. This work eliminates the possibility that a MauG-based methionine radical species accumulates during the self-reduction of bis-Fe(IV) MauG.

show abstract

Section: Discussionmentioning

confidence: 99%

Radical Trapping Study of the Relaxation of bis-Fe(IV) MauG

Davis

Koto

Liu

2018

ROS

View full text Add to dashboard Cite

show abstract

“…However, if methionine acts as an antioxidant by reacting with reactive oxygen‐ and nitrogen‐derived species [9,10], it should be oxidized by both two‐ and one‐electron mechanisms [11,12]. Indeed, the oxidation of free and peptide‐bound methionine to radical intermediates has been demonstrated before [11–15]. Likewise, methionine oxidation beyond the sulfoxide level may occur, particularly through one‐electron mechanisms because methionine sulfone has rarely been detected under physiological conditions [1].…”

Section: Introductionmentioning

confidence: 99%

Radical production from free and peptide‐bound methionine sulfoxide oxidation by peroxynitrite and hydrogen peroxide/iron(II)

et al. 2003

View full text Add to dashboard Cite

Methionine sulfoxide is a post-translational protein modi¢cation that has been receiving increasing attention in the literature. Here we used electron paramagnetic resonance spin trapping techniques to show that free and peptide-bound methionine sulfoxide is oxidized by hydrogen peroxide/iron(II)-EDTA and peroxynitrite through the intermediacy of the hydroxyl radical to produce both c CH 3 and c CH 2 CH 2 CH radicals. The results indicate that methionine sulfoxide residues are important targets of reactive oxygen-and nitrogen-derived species in proteins. Since the produced protein-derived radicals can propagate oxidative damage, the results add a new antioxidant route for the action of the enzyme peptide methionine sulfoxide reductase.

show abstract

“…These results suggested that ionizing radiation elicits epigenetic changes mediated by oxidative stress. It is reasonable to speculate that the initial seeds of methylation are formed by a free radical mechanism because methyl radicals are generated by the γ -irradiation of methionine, an endogenous molecule (31) .…”

Section: Discussionmentioning

confidence: 99%

“…When RNA was reacted with this system, 8-methylguanine, 2-methyladenine, and 8-methyladenine were detected in the acid hydrolysate. Makino (31) reported methyl radical production in a γ -irradiated aqueous solution of dl -methionine, as detected by ESR spectroscopy. Nakao et al (32) reported that both free and peptide-bound MetO are oxidized by hydrogen peroxide/iron(II)-EDTA and peroxynitrite, through a hydroxyl radical intermediate, to produce a methyl radical.…”

Section: Generation Of Methyl Radicals and Their Reactions With Nuclementioning

confidence: 99%

Free radical-mediated cytosine C-5 methylation triggers epigenetic changes during carcinogenesis

Kasai

Kawai

2013

BioMolecular Concepts

View full text Add to dashboard Cite

The methylation of the C-5 position of deoxycytidine (dC) in the promoter regions of tumor suppressor genes is often observed in cancer cells. We found that various environmental agents, as well as endogenous compounds such as methionine sulfoxide (MetO), generate methyl radicals and modify dC to form 5-methyl-dC in DNA in vitro. We confirmed that both DNA methylation and cancer incidence in the liver were increased by the administration of MetO to oxidatively stressed mice. In this review, we summarize previous reports on methyl radical generation in vitro and in vivo and DNA modifications by methyl radicals, including our discoveries, as well as our recent experimental evidence suggesting that free radical-mediated dC methylation triggers epigenetic changes.

show abstract

Studies on spin-trapped radicals in .gamma.-irradiated aqueous solutions of DL-methionine by high performance liquid chromatography and ESR spectroscopy

Cited by 29 publications

References 5 publications

Radical Trapping Study of the Relaxation of bis-Fe(IV) MauG

Radical Trapping Study of the Relaxation of bis-Fe(IV) MauG

Radical production from free and peptide‐bound methionine sulfoxide oxidation by peroxynitrite and hydrogen peroxide/iron(II)

Free radical-mediated cytosine C-5 methylation triggers epigenetic changes during carcinogenesis

Contact Info

Product

Resources

About