Biocatalytic Systems Involving Coupled Oxidizing Enzymes

Biocatalytic Systems Involving Coupled Oxidizing Enzymes 

Using an approach involving a tubular membrane reactor in which the biocatalysts were retained, Nasufi et al. [59] reported the production of ascorbic acid by a 

In an early report to a process using three oxidoreductases, namely hydrogenase (ECl.12.2.1), lipoamide dehydrogenase (EC 1.6.4.3) and 20(3-hydroxysteroid dehydrogenase (ECl.1.1.53), a reverse micelle system was used to facilitate stereo- and site-specific reduction of apolar ketosteroids, assisted by the in situ NADH-regenerating enzyme system [61]. 

Multi-Enzyme Systems in Whoie-Ceii Biotransformations and Expression of Redox Systems in Recombinant Hosts 

In a biotransformation system designed to mediate the o-dealkylation of 7-ethoxycumarin to 7-hydroxycoumarin, the genes for the P450 from Streptomyces peucelius and putidaredoxin reductase (CamA) and putidaredoxin (CamB) from 

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Biocatalytic Systems Involving Coupled Oxidizing Enzymes... 

Bioprocesses incorporating more than one redox enzyme in an oxidative reaction system might involve, in the simplest case, two oxidizing enzymes coupled so that they act sequentially to effect two oxidation steps. A key issue in the development of such oxidative biocatalytic systems would be the determination of the values, for each enzyme involved, of the redox potentials. These can be determined by potentiometric titration using redox mediators (such as NADH) and techniques such as cyclic voltammetry or electrophoresis [44]. Knowledge of the redox potentials would facilitate the design and engineering of a process in which the two... 

Bioelectrocatalysis involves the coupling of redox enzymes with electrochemical reactions [44]. Thus, oxidizing enzymes can be incorporated into redox systems applied in bioreactors, biosensors and biofuel cells. While biosensors and enzyme electrodes are not synthetic systems, they are, essentially, biocatalytic in nature (Scheme 3.5) and are therefore worthy of mention here. Oxidases are frequently used as the biological agent in biosensors, in combinations designed to detect specific target molecules. Enzyme electrodes are possibly one of the more common applications of oxidase biocatalysts. Enzymes such as glucose oxidase or cholesterol oxidase can be combined with a peroxidase such as horseradish peroxidase. 

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