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1.
Adv Appl Microbiol ; 105: 51-86, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30342723

RESUMO

Two seemingly distinct fields, industrial biocatalysis and microbial electrosynthesis, can be viewed together through the lens of electrochemical bioreactor technology in order to highlight the challenges that exist in creating a versatile platform technology for use in chemical and biological applications. Industrial biocatalysis applications requiring NAD(P)H to perform redox transformations often necessitate convoluted coupled-enzyme regeneration systems to regenerate reduced cofactor, NAD(P)H from oxidized cofactor, NAD(P). Renewed interest in continuously recycling the cofactor via electrochemical reduction is motivated by the low cost of performing electrochemical reactions, easy monitoring of the reaction progress, and straightforward product recovery. However, electrochemical cofactor regeneration methods invariably produce adventitious reduced cofactor side products which result in unproductive loss of input NAD(P). Microbial electrosynthesis is a form of microbially driven catalysis in which electricity is supplied to living microorganisms for the production of industrially relevant chemical products at higher carbon efficiencies and yields compared with traditional, nonelectrically driven, fermentations. The fundamental biochemistry of these organisms as related to selected biochemical redox processes will be explored in order to highlight opportunities to devise strategies for taking advantage of these biochemical processes in engineered systems.


Assuntos
Biocatálise , Reatores Biológicos/microbiologia , Técnicas Eletroquímicas , Redes e Vias Metabólicas/genética , NAD/metabolismo , Oxirredução
2.
PLoS One ; 15(11): e0242109, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33180865

RESUMO

Electrochemical bioreactor systems have enjoyed significant attention in the past few decades, particularly because of their applications to biobatteries, artificial photosynthetic systems, and microbial electrosynthesis. A key opportunity with electrochemical bioreactors is the ability to employ cofactor regeneration strategies critical in oxidative and reductive enzymatic and cell-based biotransformations. Electrochemical cofactor regeneration presents several advantages over other current cofactor regeneration systems, such as chemoenzymatic multi-enzyme reactions, because there is no need for a sacrificial substrate and a recycling enzyme. Additionally, process monitoring is simpler and downstream processing is less costly. However, the direct electrochemical reduction of NAD(P)+ on a cathode may produce adventitious side products, including isomers of NAD(P)H that can act as potent competitive inhibitors to NAD(P)H-requiring enzymes such as dehydrogenases. To overcome this limitation, we examined how nature addresses the adventitious formation of isomers of NAD(P)H. Specifically, renalases are enzymes that catalyze the oxidation of 1,2- and 1,6-NAD(P)H to NAD(P)+, yielding an effective recycling of unproductive NAD(P)H isomers. We designed several mutants of recombinant human renalase isoform 1 (rhRen1), expressed them in E. coli BL21(DE3) to enhance protein solubility, and evaluated the activity profiles of the renalase variants against NAD(P)H isomers. The potential for rhRen1 to be employed in engineering applications was then assessed in view of the enzyme's stability upon immobilization. Finally, comparative modeling was performed to assess the underlying reasons for the enhanced solubility and activity of the mutant enzymes.


Assuntos
Microbiologia Industrial/métodos , Monoaminoxidase/química , Estabilidade Enzimática , Escherichia coli , Humanos , Monoaminoxidase/genética , Monoaminoxidase/metabolismo , Mutação , NADP/metabolismo , Domínios Proteicos , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Solubilidade , Eletricidade Estática
3.
Biotechnol Adv ; 36(1): 120-131, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29030132

RESUMO

Industrial enzymatic reactions requiring 1,4-NAD(P)H2 to perform redox transformations often require convoluted coupled enzyme regeneration systems to regenerate 1,4-NAD(P)H2 from NAD(P) and recycle the cofactor for as many turnovers as possible. Renewed interest in recycling the cofactor via electrochemical means is motivated by the low cost of performing electrochemical reactions, easy monitoring of the reaction progress, and straightforward product recovery. However, electrochemical cofactor regeneration methods invariably produce adventitious reduced cofactor side products which result in unproductive loss of input NAD(P). We review various literature strategies for mitigating adventitious product formation by electrochemical cofactor regeneration systems, and offer insight as to how a successful electrochemical bioreactor system could be constructed to engineer efficient 1,4-NAD(P)H2-dependent enzyme reactions of interest to the industrial biocatalysis community.


Assuntos
Reatores Biológicos , Técnicas Eletroquímicas , NADP/metabolismo , NAD/metabolismo , Biocatálise , Oxirredução , Oxirredutases
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