A integrated process for nitrilase-catalyzed asymmetric hydrolysis and easy biocatalyst recycling by introducing biocompatible biphasic system

Maximizing the potential of nitrilase: Unveiling their diversity, catalytic proficiency, and versatile applications

Nitrilases represent a distinct class of enzymes that play a pivotal role in catalyzing the hydrolysis of nitrile compounds, leading to the formation of corresponding carboxylic acids. These enzymatic entities have garnered significant attention across a spectrum of industries, encompassing pharmaceuticals, agrochemicals, and fine chemicals. Moreover, their significance has been accentuated by mounting environmental pressures, propelling them into the forefront of biodegradation and bioremediation endeavors. Nevertheless, the natural nitrilases exhibit intrinsic limitations such as low thermal stability, narrow substrate selectivity, and inadaptability to varying environmental conditions. In the past decade, substantial efforts have been made in elucidating the structural underpinnings and catalytic mechanisms of nitrilase, providing basis for engineering of nitrilases. Significant breakthroughs have been made in the regulation of nitrilases with ideal catalytic properties and application of the enzymes for industrial productions. This review endeavors to provide a comprehensive discourse and summary of recent research advancements related to nitrilases, with a particular emphasis on the elucidation of the structural attributes, catalytic mechanisms, catalytic characteristics, and strategies for improving catalytic performance of nitrilases. Moreover, the exploration extends to the domain of process engineering and the multifarious applications of nitrilases. Furthermore, the future development trend of nitrilases is prospected, providing important guidance for research and application in the related fields.

Green synthesis aspects of (R)-(-)-mandelic acid; a potent pharmaceutically active agent and its future prospects

(R)-(-)-mandelic acid is an important carboxylic acid known for its numerous potential applications in the pharmaceutical industry as it is an ideal starting material for the synthesis of antibiotics, antiobesity drugs and antitumor agents. In past few decades, the synthesis of (R)-(-)-mandelic acid has been undertaken mainly through the chemical route. However, chemical synthesis of optically pure (R)-(-)-mandelic acid is difficult to achieve at an industrial scale. Therefore, its microbe mediated production has gained considerable attention as it exhibits many merits over the chemical approaches. The present review focuses on various biotechnological strategies for the production of (R)-(-)-mandelic acid through microbial biotransformation and enzymatic catalysis; in particular, an analysis and comparison of the synthetic methods and different enzymes. The wild type as well as recombinant microbial strains for the production of (R)-(-)-mandelic acid have been elucidated. In addition, different microbial strategies used for maximum bioconversion of mandelonitrile into (R)-(-)-mandelic acid are discussed in detail with regard to higher substrate tolerance and maximum bioconversion.HighlightsMandelonitrile, mandelamide and o-chloromandelonitrile can be used as substrates to produce (R)-(-)-mandelic acid by enzymes.Three enzymes (nitrilase, nitrile hydratase and amidase) are systematically introduced for production of (R)-(-)-mandelic acid.Microbial transformation is able to produce optically pure (R)-(-)-mandelic acid with 100% productive yield.

Biocatalytic dynamic reductive kinetic resolution of aryl α-chloro β-keto esters: divergent, stereocontrolled synthesis of diltiazem, clentiazem, and siratiazem

The first systematic study of ketoreductase (KRED)-catalyzed dynamic reductive kinetic resolution (DYRKR) on aryl α-chloro β-keto esters was performed, and 15 structurally diverse chiral anti-aryl α-chloro β-hydroxy esters were synthesized in 74-98% isolated yields, along with moderate-to-excellent diastereoselectivity (up to >99 : 1 dr) and good-to-excellent enantioselectivity (mostly >99% ee). LfSDR1-catalyzed complete reduction of 100 g L^-1 of substrate 6b at a ten-gram scale was achieved with a continuous fed-batch strategy, affording anti-(2S,3S)-1b, the key intermediate of diltiazem, in a record-breaking space-time yield of 96 g L^-1 d^-1. An eight-step synthesis of diltiazem, clentiazem, and siratiazem was accomplished in 32-45% overall yields, featuring this versatile biocatalytic reduction reaction as well as an efficient, green chlorination reaction in flow.

Constitutive expression of nitrilase from Rhodococcus zopfii for efficient biosynthesis of 2-chloronicotinic acid

2-chloronicotinic acid (2-CA) is a key precursor for the synthesis of a series of pesticides and pharmaceuticals. Nitrilase-catalyzed bioprocess is a promising method for 2-CA production from 2-chloronicotinonitrile (2-CN). In this study, a mutant of nitrilase from Rhodococcus zopfii (RzNIT/W167G) was constitutively overexpressed with Escherichia coli as host, which exhibited a onefold increase in enzymatic activity compared with inducible expression. Biosynthesis of 2-CA using whole cells harboring nitrilase as biocatalysts were investigated and 318.5 mM 2-CA was produced, which was the highest level for 2-CA production catalyzed by nitrilase to date. 2-CA was recovered from the reaction mixture through a simple acidification step with a recovery yield of 90%. This study developed an efficient bioprocess for 2-CA with great potential for industrial application.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-022-03119-0.

Applications of Ionic Liquids in Whole-Cell and Isolated Enzyme Biocatalysis

Ionic liquids have unique chemical properties that have fascinated scientists in many fields. The effects of adding ionic liquids to biocatalysts are many and varied. The uses of ionic liquids in biocatalysis include improved separations and phase behaviour, reduction in toxicity, and stabilization of protein structures. As the ionic liquid state of the art has progressed, concepts of what can be achieved in biocatalysis using ionic liquids have evolved and more beneficial effects have been discovered. In this review ionic liquids for whole-cell and isolated enzyme biocatalysis will be discussed with an emphasis on the latest developments, and a look to the future.

Whole-cell biocatalytic synthesis of S-(4-chlorophenyl)-(pyridin-2-yl) methanol in a liquid-liquid biphasic microreaction system

This work aims to synthesize S-(4-chlorophenyl)-(pyridin-2-yl) methanol (S-CPMA) in a green, economic, and efficient way. In the water-cyclohexane liquid-liquid system, recombinant Escherichia coli (E. coli) was used as a whole-cell catalyst and retained > 60% of its catalytic activity after five reuse cycles. In situ accumulation of the substrate/product in the organic phase effectively improves substrate tolerance and reduces product inhibition and toxicity. Meanwhile, a microreaction system consisting of membrane dispersion and three-dimensional (3D) bending-microchannel was developed to successfully generate droplet swarms with an average diameter of 30 μm. Large specific surface area provided high mass transfer efficiency between phases. While the analogous reaction in a traditional stirred tank required > 270 min to achieve a yield of > 99%, in this biphasic microreaction system, the yield reached 99.6% with a high enantiomeric excess (ee) of > 99% in only 80 min. Efficient synthesis was achieved by reducing the time by 70%.

Advances in deep eutectic solvents and water: applications in metal- and biocatalyzed processes, in the synthesis of APIs, and other biologically active compounds

This review highlights recent advances in metal- and biocatalyzed transformations, in the synthesis of APIs and other biologically active compounds, when employing deep eutectic solvents and water as environmentally responsible solvents.