Electrochemical regeneration of redox cofactors and mediators ? The key to bioelectrosynthesis

Allen, Pauline M.; Bowen, W. Richard

doi:10.1016/0167-7799(85)90103-9

Cited by 24 publications

(6 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…from −0.5 V to −0.6 V vs. NHE, with increasing cofactor concentration, suggesting a limitation associated to the heterogeneous electron transfer kinetics, which might be due to fouling effects or the dimerization of NAD radicals to (NAD) 2 at −0.7 V vs. NHE. 26,27 The experiments at pH 9.0 show the postulated results: No protons are available for a transfer from the redox mediator to NAD + . Any electrocatalytic response is not received and only the oxidation and reduction peaks of the redox mediator are visible.…”

Section: Resultsmentioning

confidence: 89%

“…The spatial separation of redox mediator and enzyme by charged polymers could represent a good alternative. Another alternative is the change of the redox mediator to methylviologen in the presence of diaphorase which has already been described in literature 27,31 or a directed and covalent immobilization of dehydrogenases with a supplemental cysteine-tag modification onto gold electrodes via thiol bonds. 32 The spatial separation of directed immobilized enzyme can also operate by charged polymers.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Electrochemical Screening of Redox Mediators for Electrochemical Regeneration of NADH

Gajdzik

Lenz

Natter

et al. 2011

J. Electrochem. Soc.

View full text Add to dashboard Cite

We report the electrochemical cofactor regeneration for electroenzymatic reduction as a promising alternative to the enzymatic recycling due to the avoidance of couple products. In the mediated electron transfer reaction appropriate redox mediators for the cofactor reduction are necessary. We have synthesized different redox mediators-based on rhodium complexes-and have screened their electrochemical performance at different pH values and concentrations. Suitable mediators have been tested in the presence of the cofactor NAD + and then additionally in the presence of D-sorbitol dehydrogenase (DSDH) from Rhodobacter sphaeroides. The electroenzymatically generated product was analyzed by HPLC. As result of the screening some mediator species were identified which enable an efficient electrochemical cofactor reduction.Biofunctionalization of metal surfaces is widely used in the field of analytical applications especially in clinical diagnostics or for biofuel cells. 1-3 But electrochemical cofactor regeneration can also be important for preparative applications like synthesis of enantiomerically pure fine chemicals as synthons in the pharmaceutical industry. Especially for the preparative conversion with dehydrogenases, which implies a mediated electron transfer from the enzyme to the electrode, a cofactor and a redox mediator are necessary. The redox mediator decreases the potential for the NAD + reduction which amounts to about −1.0 V vs. NHE at bare electrodes without mediator. 4 For preparative syntheses only catalytic amounts of the cofactor NAD + /NADH are necessary which can be recycled in an enzymatic way. 5 A promising alternative represents the electrochemical cofactor regeneration which is already extensively known for the electrochemical re-oxidation of NADH by the functionalization of metal surfaces with biomolecules in the research of biosensors and biofuel cells 6-9 but only few mediators for reduction of NAD + are known. Numerous mediators likely to oxidize NADH (i.e., NAD + regeneration) have been reported. 10 For example, the regeneration of NAD + cofactor by a nitro fluorenone redox mediator was intensively investigated by Mano and co-workers. [11][12][13] In this case, the redox mediator was covalently bound to a gold surface and the cofactor was attached to the mediator by electrostatic forces via calcium bridges. This has been notably applied in the field of bioelectrocatalysis using a modified variant of a dehydrogenase for electroenzymatic oxidation reactions 14 on the basis of a cysteine modified galactitol dehydrogenase from Rhodobacter spaeroides, which was directly immobilized onto a gold surface, leading to successful electrochemical regeneration of the cofactor.On the other hand, elaborating redox mediators enabling the onestep transfer of two electrons (or one hydride) to NAD + species to regenerate directly the active form of the reduced cofactor (i.e., 1,4-NADH) is not an easy task as such mediator should react with NAD + and not transferring directly the electrons (or hydride ion) t...

show abstract

Section: Resultsmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Electrochemical Screening of Redox Mediators for Electrochemical Regeneration of NADH

Gajdzik

Lenz

Natter

et al. 2011

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…In this study, an electron carrier, methyl viologen, was used to alter the electron flow (Kim and Kim, 1988;Peguin et al, 1994;Mutharasan, 1986, 1987). Methyl viologen was chosen because it satisfies a number of requirements as a good electron mediator (Allen and Bowen, 1985), and it can replace FdH 2 in all reactions in which this protein is involved. Methyl viologen competes with FdH 2 for the active site of hydrogenase (Ad- (Rao and Mutharasan, 1987).…”

Section: Ab Fermentation Under Various Conditionsmentioning

confidence: 99%

Metabolism analysis and on-line physiological state diagnosis of acetone–butanol fermentation

Chauvatcharin

Siripatana

Seki

et al. 1998

Biotechnol. Bioeng.

View full text Add to dashboard Cite

“…One possibility of overcoming product inhibition is the use of an extractive enzyme membrane reactor (EEMR). [8][9][10][11][12][13][14][15][16] The hydrophobic product is extracted with an organic solvent conveniently using a phase contactor module, whilst the enzyme is retained by means of ultrafiltration. 11,12 Suitable and versatile catalysts still have to be discovered for the preparation of S-enantiomers of 1,2-diols via reduction of ketones.…”

Section: Introductionmentioning

confidence: 99%

“…The concentration of the inhibitor must be low for the reaction to commence at reasonable rate. One possibility of overcoming product inhibition is the use of an extractive enzyme membrane reactor (EEMR). − The hydrophobic product is extracted with an organic solvent conveniently using a phase contactor module, whilst the enzyme is retained by means of ultrafiltration. , …”

Section: Introductionmentioning

confidence: 99%

Resolution of 1,2-Diols by Enzyme-Catalyzed Oxidation with Anodic, Mediated Cofactor Regeneration in the Extractive Membrane Reactor: Gaining Insight by Adaptive Simulation

Degenring¹,

Schröder²,

Wandrey³

et al. 2004

Org. Process Res. Dev.

View full text Add to dashboard Cite

Oxidative racemic resolution of 1,2-diols is a method for the synthesis of enantiopure diols not easily accessed by reduction. The constraints generally found for oxidation to hydroxy ketones can be overcome by coupling various techniques. To circumvent product inhibition, a membrane reactor with solvent extraction of the lipophilic product was chosen. For the oxidative regeneration of NAD+ from NADH anodic oxidation mediated by ABTS was used. The kinetic characteristics of the system were determined independently for each significant system step. However, it proved difficult to simulate the coupled process completely with the kinetic data obtained independently, as true reaction conditions are not covered by kinetic experiments. A mixed approach using a system of ordinary differential equations corrected with data from the process (e.g. enzyme activity) leads to a satisfactory description. This model was applied as a starting point for identifying the relevant process parameters.

show abstract

Electrochemical regeneration of redox cofactors and mediators ? The key to bioelectrosynthesis

Cited by 24 publications

References 4 publications

Electrochemical Screening of Redox Mediators for Electrochemical Regeneration of NADH

Electrochemical Screening of Redox Mediators for Electrochemical Regeneration of NADH

Metabolism analysis and on-line physiological state diagnosis of acetone–butanol fermentation

Resolution of 1,2-Diols by Enzyme-Catalyzed Oxidation with Anodic, Mediated Cofactor Regeneration in the Extractive Membrane Reactor: Gaining Insight by Adaptive Simulation

Contact Info

Product

Resources

About