Multi-Enzymatic Cascades In Vitro

The combination of enzymatic reactions in a simultaneous or sequential fashion by designing artificial synthetic cascades allows for the synthesis of complex compounds from simple precursors. Such multi-catalytic cascade reactions not only bear a great potential to minimize downstream processing steps but can also lead to a drastic reduction of the produced waste. With the growing toolbox of biocatalysts, alternative routes employing enzymatic transformations towards manifold and diverse target molecules become accessible. In vitro cascade reactions open up new possibilities for efficient regeneration of the required cofactors such as nicotinamide cofactors or nucleoside triphosphates. They are represented by a vast array of two-enzyme cascades that have been designed by coupling the activity of a cofactor regenerating enzyme to the product generating enzyme. However, the implementation of cascade reactions requires careful consideration, particularly with respect to whether the pathway is constructed concurrently or sequentially. In this regard, this chapter describes how biocatalytic cascades are classified, and how such cascade reactions can be employed in order to solve synthetic problems. Recent developments in the area of dynamic kinetic resolution or cofactor regeneration and showcases are presented. We also highlight the factors that influence the design and implementation of purely enzymatic cascades in one-pot or multi-step pathways in an industrial setting

Enzyme engineering of a membrane-bound monooxygenase as key step of an artificial metabolic pathway towards Tulipalin A

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The Synthesis of Chiral Gamma-Lactones by Merging Decatungstate Photocatalysis with Biocatalysis

The implementation of light-driven catalytic processes in biocatalysis opens a golden window of opportunities. We hereby report the merging of photocatalytic C-C bond formation with enzymatic asymmetric reduction for the direct conversion of simple aldehydes and acrylates or unsaturated carboxylic acids into chiral ?-lactones. Tetrabutylammonium decatungstate (TBADT) is employed as the photocatalyst to trigger the hydroacylation of the starting olefins, yielding the corresponding keto esters/acids. Subsequently, an alcohol dehydrogenase converts the intermediate to the chiral alcohol, which undergoes lactonization to the desired ?-lactone. The photochemoenzymatic synthesis of aliphatic and aromatic ?-lactones was thereby achieved with up to >99 % ee  and >99 % yield. This synthesis highlights the power of building molecular complexity by merging photocatalysis with biocatalysis to access high-value added chiral compounds from simple, cheap and largely available starting materials

Исследование методов и реализация алгоритмов выявления скрытых закономерностей параметров при определении типа сахарного диабета на основе машинного обучения

Работа направлена на выявление скрытых закономерностей параметров при определении типа сахарного диабета на основе статистических методов. Полученные результаты будут положены в основу определения характеристических признаков (фичи) искусственных нейронных сетей. Планируется проведение сравнительного анализа результатов классификации, полученных на основе алгоритмов машинного обучения.The work is aimed at identifying hidden patterns of parameters in determining the type of diabetes mellitus based on statistical methods. The obtained results will be used as a basis for determining the characteristics (features) of artificial neural networks. It is planned to conduct a comparative analysis of the classification results obtained on the basis of machine learning algorithms

Internal Illumination to Overcome the Cell Density Limitation in the Scale-up of Whole-Cell Photobiocatalysis

Cyanobacteria have the capacity to use photosynthesis to fuel their metabolism, which makes them highly promising production systems for the sustainable production of chemicals. Yet, their dependency on visible light limits the cell‐density, which is a challenge for the scale‐up. Here, it was shown with the example of a light‐dependent biotransformation that internal illumination in a bubble column reactor equipped with wireless light emitters (WLEs) could overcome this limitation. Cells of the cyanobacterium Synechocystis sp. PCC 6803 expressing the gene of the ene‐reductase YqjM were used for the reduction of 2‐methylmaleimide to (R)‐2‐methylsuccinimide with high optical purity (>99 % ee). Compared to external source of light, illumination by floating wireless light emitters allowed a more than two‐fold rate increase. Under optimized conditions, product formation rates up to 3.7 mm h(−1) and specific activities of up to 65.5 U g(DCW) (−1) were obtained, allowing the reduction of 40 mm 2‐methylmaleimide with 650 mg isolated enantiopure product (73 % yield). The results demonstrate the principle of internal illumination as a means to overcome the intrinsic cell density limitation of cyanobacterial biotransformations, obtaining high reaction rates in a scalable photobioreactor

Rational Design of Resveratrol O-methyltransferase for the Production of Pinostilbene

Pinostilbene is a monomethyl ether analog of the well-known nutraceutical resveratrol. Both compounds have health-promoting properties, but the latter undergoes rapid metabolization and has low bioavailability. O-methylation improves the stability and bioavailability of resveratrol. In plants, these reactions are performed by O-methyltransferases (OMTs). Few efficient OMTs that monomethylate resveratrol to yield pinostilbene have been described so far. Here, we report the engineering of a resveratrol OMT from Vitis vinifera (VvROMT), which has the highest catalytic efficiency in di-methylating resveratrol to yield pterostilbene. In the absence of a crystal structure, we constructed a three-dimensional protein model of VvROMT and identified four critical binding site residues by applying different in silico approaches. We performed point mutations in these positions generating W20A, F24A, F311A, and F318A variants, which greatly reduced resveratrol’s enzymatic conversion. Then, we rationally designed eight variants through comparison of the binding site residues with other stilbene OMTs. We successfully modified the native substrate selectivity of VvROMT. Variant L117F/F311W showed the highest conversion to pinostilbene, and variant L117F presented an overall increase in enzymatic activity. Our results suggest that VvROMT has potential for the tailor-made production of stilbenes.This research was funded by PROYECTO INTERDISCIPLINA-VRI-UC-II160020, number 3514-913, Pontificia Universidad Católica de Chile (to L.P.P. and A.S.) and BECA DE DOCTORADO NACIONAL 2016, number 21161084, National Agency for Research and Development (ANID), Chile (to D.P.H.), for which we are grateful. The APC was funded by Pontificia Universidad Católica de Chile

A Structural View on the Stereospecificity of Plant Borneol‐Type Dehydrogenases

The development of sustainable processes for the valorization of byproducts and other waste streams remains an ongoing challenge in the field of catalysis. Racemic borneol, isoborneol and camphor are currently produced from alpha-pinene, a side product from the production of cellulose. The pure enantiomers of these monoterpenoids have numerous applications in cosmetics and act as reagents for asymmetric synthesis, making an enzymatic route for their separation into optically pure enantiomers a desirable goal. Known short-chain borneol-type dehydrogenases (BDHs) from plants and bacteria lack the required specificity, stability or activity for industrial utilization. Prompted by reports on the presence of pure (-)-borneol and (-)-camphor in essential oils from rosemary, we set out to investigate dehydrogenases from the genus Salvia and discovered a dehydrogenase with high specificity (E>120) and high specific activity (>0.02 U mg(-1)) for borneol and isoborneol. Compared to other specific dehydrogenases, the one reported here shows remarkably higher stability, which was exploited to obtain the first three-dimensional structure of an enantiospecific borneol-type short-chain dehydrogenase. This, together with docking studies, led to the identification of a hydrophobic pocket in the enzyme that plays a crucial role in the stereo discrimination of bornane-type monoterpenoids. The kinetic resolution of borneol and isoborneol can be easily integrated into the existing synthetic route from alpha-pinene to camphor thereby allowing the facile synthesis of optically pure monoterpenols from an abundant renewable source

CryoEM analysis of small plant biocatalysts at sub 2 resolution

Enzyme catalysis has emerged as a key technology for developing efficient, sustainable processes in the chemical, biotechnological and pharmaceutical industries. Plants provide large and diverse pools of biosynthetic enzymes that facilitate complex reactions, such as the formation of intricate terpene carbon skeletons, with exquisite specificity. High resolution structural analysis of these enzymes is crucial in order to understand their mechanisms and modulate their properties by targeted engineering. Although cryo electron microscopy cryoEM has revolutionized structural biology, its applicability to high resolution structural analysis of comparatively small enzymes has so far been largely unexplored. Here, it is shown that cryoEM can reveal the structures of plant borneol dehydrogenases of amp; 8764;120 kDa at or below 2 resolution, paving the way for the rapid development of new biocatalysts that can provide access to bioactive terpenes and terpenoid

Photosynthetically produced sucrose by immobilized Synechocystis sp. PCC 6803 drives biotransformation in E. coli

Background: Whole-cell biotransformation is a promising emerging technology for the production of chemicals. When using heterotrophic organisms such as E. coli and yeast as biocatalysts, the dependence on organic carbon source impairs the sustainability and economic viability of the process. As a promising alternative, photosynthetic cyanobacteria with low nutrient requirements and versatile metabolism, could ofer a sustainable platform for the heterologous production of organic compounds directly from sunlight and CO2. This strategy has been applied for the photoautotrophic production of sucrose by a genetically engineered cyanobacterium, Synechocystis sp. PCC 6803 strain S02. As the key concept in the current work, this can be further used to generate organic carbon compounds for diferent heterotrophic applications, including for the whole-cell biotransformation by yeast and bacteria. Results: Entrapment of Synechocystis S02 cells in Ca2+-cross-linked alginate hydrogel beads improves the specifc sucrose productivity by 86% compared to suspension cultures during 7 days of cultivation under salt stress. The process was further prolonged by periodically changing the medium in the vials for up to 17 days of efcient production, giving the fnal sucrose yield slightly above 3000 mg l −1 . We successfully demonstrated that the medium enriched with photosynthetically produced sucrose by immobilized Synechocystis S02 cells supports the biotransformation of cyclohexanone to ε-caprolactone by the E. coli WΔcscR Inv:Parvi strain engineered to (i) utilize low concentrations of sucrose and (ii) perform biotransformation of cyclohexanone to ε-caprolactone. Conclusion: We conclude that cell entrapment in Ca2+-alginate beads is an efective method to prolong sucrose production by the engineered cyanobacteria, while allowing efcient separation of the cells from the medium. This advantage opens up novel possibilities to create advanced autotroph–heterotroph coupled cultivation systems for solar-driven production of chemicals via biotransformation, as demonstrated in this work by utilizing the photosynthetically produced sucrose to drive the conversion of cyclohexanone to ε-caprolactone by engineered E. coli.</p

GPCRDB: information system for G protein-coupled receptors

The GPCRDB is a Molecular Class-Specific Information System (MCSIS) that collects, combines, validates and disseminates large amounts of heterogeneous data on G protein-coupled receptors (GPCRs). The GPCRDB contains experimental data on sequences, ligand-binding constants, mutations and oligomers, as well as many different types of computationally derived data such as multiple sequence alignments and homology models. The GPCRDB provides access to the data via a number of different access methods. It offers visualization and analysis tools, and a number of query systems. The data is updated automatically on a monthly basis. The GPCRDB can be found online at http://www.gpcr.org/7tm/