ATP cofactor regeneration via the glycolytic pathway

Round, round we go - strategies for enzymatic cofactor regeneration

Covering: up to the beginning of 2020Enzymes depending on cofactors are essential in many biosynthetic pathways of natural products. They are often involved in key steps: catalytic conversions that are difficult to achieve purely with synthetic organic chemistry. Hence, cofactor-dependent enzymes have great potential for biocatalysis, on the condition that a corresponding cofactor regeneration system is available. For some cofactors, these regeneration systems require multiple steps; such complex enzyme cascades/multi-enzyme systems are (still) challenging for in vitro biocatalysis. Further, artificial cofactor analogues have been synthesised that are more stable, show an altered reaction range, or act as inhibitors. The development of bio-orthogonal systems that can be used for the production of modified natural products in vivo is an ongoing challenge. In light of the recent progress in this field, this review aims to provide an overview of general strategies involving enzyme cofactors, cofactor analogues, and regeneration systems; highlighting the current possibilities for application of enzymes using some of the most common cofactors.

Production of L-Theanine Using Escherichia coli Whole-Cell Overexpressing γ-Glutamylmethylamide Synthetase with Bakers Yeast

L-Theanine, found in green tea leaves has been shown to positively affect immunity and relaxation in humans. There have been many attempts to produce L-theanine through enzymatic synthesis to overcome the limitations of traditional methods. Among the many genes coding for enzymes in the L-theanine biosynthesis, glutamylmethylamide synthetase (GMAS) exhibits the greatest possibility of producing large amounts of production. Thus, GMAS from Methylovorus mays No. 9 was overexpressed in several strains including vectors with different copy numbers. BW25113(DE3) cells containing the pET24ma::gmas was selected for strains. The optimal temperature, pH, and metal ion concentration were 50°C, 7, and 5 mM MnCl2, respectively. Additionally, ATP was found to be an important factor for producing high concentration of L-theanine so several strains were tested during the reaction for ATP regeneration. Bakers yeast was found to decrease the demand for ATP most effectively. Addition of potassium phosphate source was demonstrated by producing 4-fold higher L-theanine. To enhance the conversion yield, GMAS was additionally overexpressed in the system. A maximum of 198 mM L-theanine was produced with 16.5 mmol/l/h productivity. The whole-cell reaction involving GMAS has greatest potential for scale-up production of L-theanine.

Emerging enzymes for ATP regeneration in biocatalytic processes

Adenosine-5'-triphosphate-dependent enzyme catalysed reactions are widespread in nature. Consequently, the enzymes involved have an intrinsic potential for use in syntheses of high value products. Although regeneration systems for ATP starting from adenosine-5'-diphosphate are available, certain limitations exist for both in vitro and in vivo applications requiring ATP regeneration from adenosine-5'-monophosphate, or adenosine. Following a short overview of the chemical and thermodynamic background, this Minireview focuses on emerging enzymes and methodologies for ATP regeneration. A large range of as yet unexploited reactions will be accessible with new, powerful, multistep ATP regeneration systems that use cheap phosphate donors and provide high longevity, compatibility, and robustness under process conditions. Their potential might go far beyond the direct use of ATP in enzymatic reactions; enzyme discovery, and engineering, as well as immobilisation strategies, will help to realise such systems.

Genetically engineered synthesis of natural products: from alkaloids to corrins

Because many natural products are of biological and medicinal importance, methods are continually being sought for studying their biosynthetic pathways, which may eventually result in increased production and the generation of novel compounds. Advances in genetic engineering have enabled the homologous or heterologous expression of many natural product biosynthetic genes from divergent sources, resulting in a supply of enzymes not readily available by isolation from the producing organism. Mixing and matching of these enzymes in cell-free reactions can provide information, not available by any other means, about enzyme mechanisms, pathway intermediates, and possible variations in the structure of the final product.