Combination of Asymmetric Organo- and Biocatalysis in Flow Processes and Comparison with their Analogous Batch Syntheses

A sequential-type as well as a tandem-type chemoenzymatic flow cascade combining an organocatalytic aldol reaction and a biocatalytic reduction to form stereoselectively a 1,3-diol with two stereogenic centers were developed. Initially, a comprehensive screening of 24 alcohol dehydrogenases was carried out and the identified candidates were...

Reconsidering hydrolysis kinetics for anaerobic digestion of waste activated sludge applying cascade reactors with ultra-short residence times

Hydrolysis is considered to be the rate-limiting step in anaerobic digestion of waste activated sludge (WAS). In this study, an innovative 4 stages cascade anaerobic digestion system was researched to (1) comprehensively clarify whether cascading configuration enhances WAS hydrolysis, and to (2) better understand the governing hydrolysis...

A second shell residue modulates a conserved ATP-binding site with radically different affinities for ATP

Background: Prediction of ligand binding and design of new function in enzymes is a time-consuming and expensive process. Crystallography gives the impression that proteins adopt a fixed shape, yet enzymes are functionally dynamic. Molecular dynamics offers the possibility of probing protein movement while predicting ligand binding....

Isothermal titration calorimetric assessment of lignin conversion by laccases

Lignin valorization may offer a sustainable approach to achieve a chemical industry that is not completely dependent on fossil resources for the production of aromatics. However, lignin is a recalcitrant, heterogeneous, and complex polymeric compound for which only very few catalysts can act in a predictable and reproducible manner. Laccase...

Compartmentalized cross-linked enzyme nano aggregates (c-CLEnAs) toward pharmaceutical transformations

A new immobilization strategy using compartmentalized nanoreactors is herein reported for two biocatalytic processes: (1)N-acetylneuraminate lyase (NAL) is internalized in NAL-c-CLEnAs and used in a continuous flow aldol condensation ofN-acetyl-d-mannosamine with sodium pyruvate toN-acetylneuraminic acid; (2) two hydroxysteroid dehydrogenases...

Pilot-scale production of peroxygenase from agrocybe aegerita

The pilot-scale production of the peroxygenase from Agrocybe aegerita (rAaeUPO) is demonstrated. In a fed-batch fermentation of the recombinant Pichia pastoris, the enzyme was secreted into the culture medium to a final concentration of 0.29 g L-1 corresponding to 735 g of the peroxygenase in 2500 L of the fermentation broth after 6 days. Due...

Laccase did it again: A scalable and clean regeneration system for NAD⁺ and its application in the synthesis of 12-oxo-hydroxysteroids

The specific oxidation of 12α-OH group of hydroxysteroids is required for the preparation of cheno-and ursodeoxycholic acid (CDCA and UDCA, respectively). The C₁₂ oxidation of hydroxysteroids into their 12-oxo derivatives can selectively be performed by employing 12α-hydroxysteroid dehydrogenases. These enzymes use NAD(P)<sup>+<...

Compartmentalized cross-linked enzymatic nano -aggregates (c -CLE n A) for efficient in-flow biocatalysis

Nano-sized enzyme aggregates, which preserve their catalytic activity are of great interest for flow processes, as these catalytic species show minimal diffusional issues, and are still sizeable enough to be effectively separated from the formed product. The realization of such catalysts is however far from trivial. The stable formation of a...

Exploring the abundance of oleate hydratases in the genus Rhodococcus—discovery of novel enzymes with complementary substrate scope

Oleate hydratases (Ohys, EC 4.2.1.53) are a class of enzymes capable of selective water addition reactions to a broad range of unsaturated fatty acids leading to the respective chiral alcohols. Much research was dedicated to improving the applications of existing Ohys as well as to the identification of undescribed Ohys with potentially novel...

Photobiocatalytic synthesis of chiral secondary fatty alcohols from renewable unsaturated fatty acids

En route to a bio-based chemical industry, the conversion of fatty acids into building blocks is of particular interest. Enzymatic routes, occurring under mild conditions and excelling by intrinsic selectivity, are particularly attractive. Here we report photoenzymatic cascade reactions to transform unsaturated fatty acids into...

Discovery and engineering of an aldehyde tolerant 2-deoxy-d-ribose 5-phosphate aldolase (Dera) from pectobacterium atrosepticum

DERA (2-Deoxy-D-ribose 5-phosphate aldolase) is the only known aldolase that accepts two aldehyde substrates, which makes it an attractive catalyst for the synthesis of a chiral polyol motif that is present in several pharmaceuticals, such as atorvastatin and pravastatin. However, inactivation of the enzyme in the presence of aldehydes...

Biocatalysis explained: From pharmaceutical to bulk chemical production

Biocatalysis is one of the most promising technologies for the sustainable synthesis of molecules for pharmaceutical, biotechnological and industrial purposes. From the gram to the ton scale, biocatalysis is employed with success. This is underpinned by the fact that the global enzyme market is predicted to increase from $7 billion to $10...

Clean Enzymatic Oxidation of 12α-Hydroxysteroids to 12-Oxo-Derivatives Catalyzed by Hydroxysteroid Dehydrogenase

The C12 specific oxidation of hydroxysteroids is an essential reaction required for the preparation of pharmaceutical ingredients like ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA), which can be synthesized by Wolff-Kishner reduction of the obtained 12-oxo-hydroxysteroids. 12α-hydroxysteroid dehydrogenases (12α-HSDHs) have...

'Clean' hydrolase reactions using commercial washing powder

We report the use of commercial laundry powder as a biocatalyst for a range of lipase-catalysed reactions including (trans)esterification, ester hydrolysis and chemoenzymatic epoxidation reactions. The enzymatic laundry powder exhibited excellent stability and recyclability, making it a readily available and cheap biocatalyst for chemical...

Energising the E-factor: The E⁺-factor

The E-factor has become an important measure for the environmental impact of (bio)chemical reactions. However, summing up the obvious wastes generated in the laboratory neglects energy-related wastes (mostly greenhouse gases) which are generated elsewhere. To estimate these wastes, we propose to extend the E-factor by an energy-term (E<sup>+<...

Latest development in the synthesis of ursodeoxycholic acid (UDCA): A critical review

Ursodeoxycholic acid (UDCA) is a pharmaceutical ingredient widely used in clinics. As bile acid it solubilizes cholesterol gallstones and improves the liver function in case of cholestatic diseases. UDCA can be obtained from cholic acid (CA), which is the most abundant and least expensive bile acid available. The now available chemical routes...

Light-Driven Enzymatic Decarboxylation of Fatty Acids

The photoenzymatic decarboxylation of fatty acids to alkanes is proposed as an alternative approach for the synthesis of biodiesel. By using a recently discovered photodecarboxylase from Chlorella variabilis NC64A (CvFAP) we demonstrate the irreversible preparation of alkanes from fatty acids and triglycerides. Several fatty acids and their...