Reactivity characteristics of cytochrome c(III) adduced from its reduction by hexaammineruthenium(II) ion

Ewall, Ralph X.; Bennett, Larry E.

doi:10.1021/ja00810a063

Cited by 68 publications

(20 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The present data indicate that ferrocytochrome c is rapidly oxidized by thiyl radicals and that the process occurs without the formation of any optically determinable intermediates. By analogy with previous studies (Seki & Imamura, 1981) the results indicate that direct one-electron transfer takes place at the exposed haem edge, the part of the redox centre available at the surface of the protein (Ewall & Bennett, 1974;McArdle et al, 1974;Cassatt & Marini, 1974). Oxidation by the thiyl radicals derived from GSH and Thiola are 100% efficient under the conditions used, though reactions involving the penicillamine and cysteine thiyl radicals were not as efficient (Table 1).…”

Section: Discussionsupporting

confidence: 82%

Thiyl free radicals and the oxidation of ferrocytochrome c Direct observation of coupled hydrogen-atom- and electron-transfer reactions

Forni¹,

Willson²

1986

Biochemical Journal

View full text Add to dashboard Cite

Absolute rate constants for the reaction of ferrocytochrome c with the thiyl radicals derived from cysteine, GSH, penicillamine and N-(2-mercaptopropionyl)glycine were measured by using the technique of pulse radiolysis. The reaction is believed to occur through a one-electron-transfer process, in agreement with the hypothesis that thiols may act as catalysts linking hydrogen-atom- and electron-transfer reactions.

show abstract

Section: Discussionsupporting

confidence: 82%

Thiyl free radicals and the oxidation of ferrocytochrome c Direct observation of coupled hydrogen-atom- and electron-transfer reactions

Forni¹,

Willson²

1986

Biochemical Journal

View full text Add to dashboard Cite

show abstract

“…46, 47 The k 22 values of Co(phen) 3 3+ and a 6 Ru 2+ , 4.5 ×10 1 mM −1 s −1 and 3 × 10 3 mM −1 s −1 , respectively, were taken from the literature. 48, 49 K 12 was calculated according to eq 6:

K_{12} = exp (\frac{n F Δ E}{R T})

…”

Section: Methodsmentioning

confidence: 99%

The K79G Mutation Reshapes the Heme Crevice and Alters Redox Properties of Cytochromec

et al. 2018

View full text Add to dashboard Cite

The two roles of cytochrome c (cyt c), in oxidative phosphorylation and apoptosis, critically depend on redox properties of its heme iron center. The K79G mutant has served as a parent protein for a series of mutants of yeast iso-1 cyt c. The mutation preserves the Met80 coordination to the heme iron, as found in WT* (K72A/C102S), and many spectroscopic properties of K79G and WT* are indistinguishable. The K79G mutation does not alter the global stability, fold, rate of Met80 dissociation, or thermodynamics of the alkaline transition (pKa) of the protein. However, the reduction potential of the heme iron decreases; further, the pKH of the trigger group and the rate of the Met-to-Lys ligand exchange associated with the alkaline transition decrease, suggesting changes in the environment of the heme. The rates of electron self-exchange and bimolecular electron transfer (ET) with positively-charged inorganic complexes increase, as does the intrinsic peroxidase activity. Analysis of the reaction rates suggests that there is increased accessibility of the heme edge in K79G and supports the importance of the Lys79 site for bimolecular ET reactions of cyt c, including those with some of its native redox partners. Structural modeling rationalizes the observed effects to arise from changes in the volume of the heme pocket and solvent accessibility of the heme group. Kinetic and structural analyses of WT* characterize the properties of the heme crevice of this commonly employed reference variant. This study highlights the important role of Lys79 for defining functional redox properties of cyt c.

show abstract

“…Reductants used to test these substrates were sodium dithionite, hexa-ammineruthenium(II) chloride, NADPH/methylviologen, titanium(III) citrate/methyl viologen, and a flavodoxin/flavodoxin-NADPH reductase system 35,47,48 .…”

Section: Extended Datamentioning

confidence: 99%

A B12-dependent radical SAM enzyme involved in oxetanocin A biosynthesis

Bridwell‐Rabb

Zhong

Sun

et al. 2017

Nature

209

View full text Add to dashboard Cite

Summary Oxetanocin-A (OXT-A, 1) is a potent antitumor, antiviral, and antibacterial compound. Biosynthesis of OXT-A has been linked to a plasmid-borne, Bacillus megaterium gene cluster that contains four genes, oxsA, oxsB, oxrA, and oxrB. Here, we show that the oxsA and oxsB genes are both required for the production of OXT-A. Biochemical analysis of the encoded proteins, a cobalamin (Cbl)-dependent S-adenosylmethionine (AdoMet) radical enzyme, OxsB, and an HD-domain phosphohydrolase, OxsA, revealed that OXT-A is derived from 2′-deoxyadenosine phosphate in an OxsB-catalyzed ring contraction reaction initiated by H-atom abstraction from C2′. Hence, OxsB represents the first biochemically characterized non-methylating Cbl-dependent AdoMet radical enzyme. X-ray analysis of OxsB reveals the fold of a Cbl-dependent AdoMet radical enzyme for which there are an estimated 7000 members. Overall, this work provides a framework for understanding the interplay of AdoMet and Cbl cofactors and expands the catalytic repertoire of Cbl-dependent AdoMet radical enzymes.

show abstract

Reactivity characteristics of cytochrome c(III) adduced from its reduction by hexaammineruthenium(II) ion

Cited by 68 publications

References 6 publications

Thiyl free radicals and the oxidation of ferrocytochrome c Direct observation of coupled hydrogen-atom- and electron-transfer reactions

Thiyl free radicals and the oxidation of ferrocytochrome c Direct observation of coupled hydrogen-atom- and electron-transfer reactions

The K79G Mutation Reshapes the Heme Crevice and Alters Redox Properties of Cytochromec

A B12-dependent radical SAM enzyme involved in oxetanocin A biosynthesis

Contact Info

Product

Resources

About