Electron Transfer Reactions in Biological Systems: The Reduction of Ferricytochrome
            <i>c</i>
            by Chromous Ions

Grimes, Carol J.; Piszkiewicz, Dennis; Fleischer, Everly B.

doi:10.1073/pnas.71.4.1408

Cited by 41 publications

(13 citation statements)

References 23 publications

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“…These studies have shown that Cr(II) is a very efficient reductant and have not revealed any evidence for there being more than one reactive species at the pH used for this work. Furthermore there is some evidence (Kowalski, 1969;Grimes et al, 1974) to suggest that, in mammalian cytochrome c at least, the Cr2+ ion reacts with the protein at the site normally concerned with the interaction with the natural reductase.…”

mentioning

confidence: 99%

The reduction of Pseudomonas cytochrome c551 oxidase by chromous ions

Barber¹,

Parr²,

Greenwood³

1977

Biochemical Journal

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The reduction of cytochrome c551 oxidase from Pseudomonas aeruginosa by Cr2+ ions was followed in the stopped-flow apparatus at a number of wavelengths. The c-haem reduction proceeded in a biphasic fashion with second-order rate constants of 2.6 X 10(5)M-1-S-1 and 4.8 X 10(4)M-1-S-1 at 25 degrees C, whereas the biphasic reduction of the d1-haem appeared to be independent of reductant concentration with rate constants of approx. 1.0S-1 and 0.25S-1 respectively. The kinetically determined difference spectra (reduced minus oxidized) for the c- and d1-haems are presented.

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mentioning

confidence: 99%

The reduction of Pseudomonas cytochrome c551 oxidase by chromous ions

Barber¹,

Parr²,

Greenwood³

1977

Biochemical Journal

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“…No one has yet described the specific reactions between Cr(II) and GSSG or NAD(P) + in detail. However, Cr(II)-induced reductions (Chau et al, 1971;Chau and Wilkinson, 1972), as well as simple electron transfer reactions with proteins (i.e., cytochromes; Grimes et al, 1974;Greenwood et al, 1977;Jones and Wilson, 1984), have been shown to occur under cell-like conditions. If Cr(II) deposited in AM is processed in this manner, it is feasible that reducing equivalent availability for NAD(P)H oxidase could be enhanced.…”

Section: Discussionmentioning

confidence: 99%

Pulmonary Immunotoxic Potentials of Metals Are Governed by Select Physicochemical Properties: Chromium Agents

Cohen

Prophete

Sisco

et al. 2006

Journal of Immunotoxicology

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Increasing the understanding of how metal ions/complexes react in situ will allow for the improved specificity and controlled toxicity of novel synthetic metallocompounds that will be used as inhaled diagnostics or therapeutics. Our previous work showed that inhalation of select metals (e.g., chromium, vanadium, nickel, iron) caused alterations in lung immune cell function and in local bacterial resistance. The data also suggested that variations in the degree of immuno-modulation induced were not solely dependent on the amount of metal deposited in the lung, but also on the specific compound. If specificity governs immunomodulatory potential, it follows that physicochemical properties inherent to the metal may have a role in the elicited effects. We hypothesize that major determinants of any metal compound's immunomodulatory potential in situ are its redox behavior, valency, and/or solubility. Using changes in local bacterial resistance as an endpoint, differences in immunotoxic potential in the lungs were quantified for a range of chromium agents (insoluble calcium chromate(VI), and soluble sodium chromate(VI), potassium bis(dipicolinato)chromate(III) and sodium bis(dipicolinato)chromate(II)). Results indicated that among the latter three forms of Cr, strongly oxidizing hexavalent Cr (Cr[VI]) had the greatest impact on resistance, while reducing divalent and fairly unreactive trivalent forms of Cr had no effect at an equal exposure level (i.e., 100 microg Cr/m(3), 5 hr/d, for 5 d). Insoluble Cr(VI) had a greater effect than its soluble form. When data was analyzed in the context of pre-infection lung Cr burdens, it was seen that immunomodulatory potentials for both Cr(VI) agents did not differ significantly; however, complexes with different oxidation states did induce varying responses, suggesting that differences in potential might be attributed to redox behavior. From this it was concluded that for Cr, certain physicochemical properties are likely more important to any in situ pulmonary immunotoxicity than others (i.e., redox behavior is more critical than solubility). Our findings, in part, will help provide a basis for understanding why certain metals could be a greater health risk than others, even when encountered in equal amounts. This, in turn, will help researchers in the design of inhalable diagnostic/therapeutic metallopharmaceuticals by pre-empting the selection of certain metal ions/complexes for potential use in these products.

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“…An affinity approach to identification of redox reagent binding sites on metalloproteins has been developed by Pecht (51-53) based in part on earlier observations by Kowalsky (54) and Fleischer and co-workers (55) on the reduction of ferricytochrome c by Cr2+. In the original reports, the Cr3+ which is formed following reduction of the protein was found to form a stable substitution-inert complex with the protein (54,55) that appeared to involve a crosslink between Asn-52 and Tyr-67 (55). From this observation, it was concluded that these residues are involved in the Cr2+ reduction pathway.…”

Section: Studies Of Bimolecular Electron Transfer Reactionsmentioning

confidence: 96%

Experimental approaches to studying biological electron transfer

Scott¹,

Mauk²,

Gray³

1985

J. Chem. Educ.

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Electron transfer reactions are central to many of the metabolic processes necessary for the survival of all organisms. Electron transport chains function as a series of consecutive electron transfer reactions between pairs of proteins which have evolved to couple efficiently the exergonic electron transfer events to energy conservation. Typically, the electrons are transferred between metal sites or organic prosthetic groups that are spatially arranged within a single protein or a complex of proteins such that the electron must traverse a considerable amount of intervening polypeptide. The observation of significant rates of electron transfer between sites separated by perhaps 20-30 A has raised the possibility that electron tunneling is the operative mechanism in these cases. The obvious importance of electron

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Electron Transfer Reactions in Biological Systems: The Reduction of Ferricytochrome c by Chromous Ions

Cited by 41 publications

References 23 publications

The reduction of Pseudomonas cytochrome c551 oxidase by chromous ions

The reduction of Pseudomonas cytochrome c551 oxidase by chromous ions

Pulmonary Immunotoxic Potentials of Metals Are Governed by Select Physicochemical Properties: Chromium Agents

Experimental approaches to studying biological electron transfer

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