ChemInform Abstract: KINETIC STUDIES OF THE REDUCTION OF FERRICYTOCHROME C BY FE(EDTA)(2‐)

Hodges, H. L.; Holwerda, Robert A.; Gray, Harry B.

doi:10.1002/chin.197429365

Cited by 7 publications

(10 citation statements)

References 1 publication

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“…Direct NOR reduction by Fe(II)EDTA 2À (reaction 6) has, to the best of our knowledge, not been reported in literature. However, Fe(II)EDTA 2À is an excellent electron donor for Cytochrome c reduction (reaction 7), as reported by Hodges et al (1974):…”

Section: Effect Of Ethanol and Fe(ii)edtamentioning

confidence: 76%

“…where the 2nd order rate constant K amounts 7.34 Â 10 4 mol L À1 s À1 at 328 K (Hodges et al, 1974), that is, the operating temperature of BioDeNOx reactors (Buisman et al, 1999) and the temperature applied in the present study. This means that, apart from direct NOR reduction, the Fe(II)EDTA 2À concentration determines the concentration of reduced Cytocrome c and therefore, indirectly, the NO reduction rate.…”

Section: Kinetics Of No Reductionmentioning

confidence: 99%

“…The Fe(II)EDTA 2À concentration likely determines the fraction of NOR that is in the reduced state, whether via direct NOR reduction (reaction 6) or indirectly via Cytochrome c reduction (reaction 7). Using horseheart Cytochrome c, Hodges et al (1974) found first order kinetics for both the Fe(II)EDTA 2À and protein concentration according to:…”

Section: Kinetics Of No Reductionmentioning

confidence: 99%

See 2 more Smart Citations

Nitric oxide reduction in BioDeNOx reactors: Kinetics and mechanism

Maas

Manconi

Klapwijk

et al. 2008

Biotech & Bioengineering

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Biological reduction of nitric oxide (NO) to di-nitrogen (N(2)) gas in aqueous Fe(II)EDTA(2-) solutions is a key reaction in BioDeNOx, a novel process for NOx removal from flue gases. The mechanism and kinetics of the first step of NO reduction, that is, the conversion of NO to N(2)O, was determined in batch experiments using various types of inocula. Experiments were performed in Fe(II)EDTA(2-) medium (5-25 mM) under BioDeNOx reactor conditions (55 degrees C, pH 7.2 +/- 0.2) with ethanol as external electron donor. BioDeNOx reactor mixed liquor gave the highest NO reduction rates (+/-0.34 nmol s(-1) mg(prot)(-1)) with an estimated K(m) value for NO lower than 10 nM. The specific NO (to N(2)O) reduction rate depended on the NO (aq) and Fe(II)EDTA(2-) concentration as well as the temperature. The experimental results, complemented with kinetic and thermodynamic considerations, show that Fe(II)EDTA(2-), and not ethanol, is the primary electron donor for NO reduction, that is, the BioDeNOx reactor medium (the redox system Fe(II)EDTA(2-)/Fe(III)EDTA(-)) interferes with the NO reduction electron transfer chain and thus enhances the NO denitrification rate.

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Section: Effect Of Ethanol and Fe(ii)edtamentioning

confidence: 76%

Section: Kinetics Of No Reductionmentioning

confidence: 99%

Section: Kinetics Of No Reductionmentioning

confidence: 99%

See 1 more Smart Citation

Nitric oxide reduction in BioDeNOx reactors: Kinetics and mechanism

Maas

Manconi

Klapwijk

et al. 2008

Biotech & Bioengineering

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“…Since NO reduction to N 2 is involved in the denitrification pathway (Zumft, 1997) and the Veendam inoculum used in this study originates from a denitrifying plant, it is likely that the two bacterial enzymes, namely, NO reductase (NOR) as well as N 2 O reductase (N 2 OR) are present in the sludge and thus are involved in the BioDeNOx regeneration process. As Fe(II)EDTA 2À is reported to be an excellent electron donor for Cytochrome c reduction (Hodges et al, 1974), which is an electron carrier for both NOR and N 2 OR (Wasser et al, 2002), the chelated ferrous iron might enhance the denitrification rates by chemical regeneration of the electron carriers.…”

Section: Regeneration Capacity/no Reductionmentioning

confidence: 99%

NOx removal from flue gas by an integrated physicochemical absorption and biological denitrification process

Maas¹,

Bosch²,

Klapwijk³

et al. 2005

Biotechnol. Bioeng.

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An integrated physicochemical and biological technique for NO(x) removal from flue gas, the so-called BioDeNO(x) process, combines the principles of wet absorption of NO in an aqueous Fe(II)EDTA(2-) solution with biological reduction of the sorbed NO in a bioreactor. The biological reduction of NO to di-nitrogen gas (N(2)) takes place under thermophilic conditions (55 degrees C). This study demonstrates the technical feasibility of this BioDeNO(x) concept in a bench-scale installation with a continuous flue gas flow of 650 l.h(-1) (70-500 ppm NO; 0.8-3.3% O(2)). Stable NO removal with an efficiency of at least 70% was obtained in case the artificial flue gas contained 300 ppm NO and 1% O(2) when the bioreactor was inoculated with a denitrifying sludge. An increase of the O(2) concentration of only 0.3% resulted in a rapid elevation of the redox potential (ORP) in the bioreactor, accompanied by a drastic decline of the NO removal efficiency. This was not due to a limitation or inhibition of the NO reduction, but to a limited biological iron reduction capacity. The latter leads to a depletion of the NO absorption capacity of the scrubber liquor, and thus to a poor NO removal efficiency. Bio-augmentation of the reactor mixed liquor with an anaerobic granular sludge with a high Fe(III) reduction capacity successfully improved the bioreactor efficiency and enabled to treat a flue gas containing at least 3.3% O(2) and 500 ppm NO with an NO removal efficiency of over 80%. The ORP in the bioreactor was found to be a proper parameter for the control of the ethanol supply, needed as electron donor for the biological regeneration process. The NO removal efficiency as well as the Fe(III)EDTA(-) reduction rate were found to decline at ORP values higher than -140 mV (pH 7.0). For stable BioDeNO(x) operation, the supply of electron donor (ethanol) can be used to control the ORP below that critical value.

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“…Hales apparently rejects vibronic coupling ideas because they often (but not invariably) lead to electron transfer distances of 5-10 A rather than 30 A scale. However, small molecules exchange electrons with cytochrome c via the almost exposed heme edge, rather than through 20 A of protein (3). Electron exchange between the a-and ,B-hemes of hemoglobin (one oxidized, one reduced) which are separated by 25 A (Fe-Fe distances) takes days (4) and is probably accomplished by mediators or heme exchange, rather than by direct electron transfer.…”

mentioning

confidence: 99%