Switching Nitrilase With Enantioselective Hydration Activity for Efficient Synthesis of Chiral 2,2-Dimethylcyclopropanecarboxamide.

Chiral 2,2-dimethylcyclopropanecarboxamides serve as important pharmaceutical intermediates. However, enantioselective synthesis of 2,2-dimethylcyclopropanecarboxamides is difficult due to the unique bond angle and rigid planar structure of the dimethylcyclopropane skeleton. Although nitrile hydratases are attractive for amide biosynthesis, their practical applications are restricted because of narrow substrate spectrum and poor enantioselectivity.

Construction of an Efficient -Succinyl--homoserine Producing Cell Factory and Its Application for Coupling Production of -Methionine and Succinic Acid.

-Succinyl--homoserine (OSH) is an important C4 platform compound with broad applications. Its green and efficient production is receiving increasing attention. Herein, the OSH producing chassic cell was constructed by deleting the transcriptional negative regulation factor, blocking the OSH consumption pathway, and inhibiting the competitive bypass pathways.

Effects of cluster nursing interventions on the prevention of pressure ulcers in intensive care units patients: A meta-analysis.

A meta-analysis was conducted to comprehensively evaluate the impact of cluster nursing interventions on the prevention of pressure ulcers (PUs) in intensive care unit (ICU) patients. Computer searches were performed in databases including Embase, Google Scholar, Cochrane Library, PubMed, Wanfang and China National Knowledge Infrastructure for randomized controlled trials (RCTs) implementing cluster nursing interventions for PUs prevention in ICU patients, with the search period covering the database inception to November 2023. Two researchers independently screened the literature, extracted data and conducted quality assessments.

Regulating substrate preference of phosphatase by reshaping the "cap domain" for multi-enzymatic biosynthesis of high-purity monosaccharides.

Phosphatases are a class of enzymes catalyzing the cleavage of monophosphate ester bonds from the phosphorylated substrates. They have important applications in construction of in vitro multi-enzymatic system for monosaccharides. However, the enzymes generally show substrate ambiguity, which has become a bottleneck for efficient biosynthesis of target products with high purity.

Improvement of multicatalytic properties of nitrilase from Paraburkholderia graminis for efficient biosynthesis of 2-chloronicotinic acid.

Nitrilases are promising biocatalysts to produce high-value-added carboxylic acids through hydrolysis of nitriles. However, since the enzymes always show low activity and sometimes with poor reaction specificity toward 2-chloronicotinonitrile (2-CN), very few robust nitrilases have been reported for efficient production of 2-chloronicotinic acid (2-CA) from 2-CN. Herein, a nitrilase from Paraburkholderia graminis (PgNIT) was engineered to improve its catalytic properties.

High-throughput assay of tyrosine phenol-lyase activity using a cascade of enzymatic reactions.

Tyrosine phenol-lyase (TPL) exhibits great potential in industrial biosynthesis of l-tyrosine and its derivates. To uncover and screen TPLs with excellent catalytic properties, there is unmet demand for development of facile and reliable screening system for TPL. Here we presented a novel assay format for the detection of TPL activity based on catechol 2,3-dioxygenase (C23O)-catalyzed reaction.

Rational Regulation of Reaction Specificity of Nitrilase for Efficient Biosynthesis of 2-Chloronicotinic Acid through a Single Site Mutation.

Nitrilase-catalyzed hydrolysis of 2-chloronicotinonitrile (2-CN) is a promising approach for the efficient synthesis of 2-chloronicotinic acid (2-CA). The development of nitrilase with ideal catalytic properties is crucial for the biosynthetic route with industrial potential. Herein, a nitrilase from Rhodococcus zopfii (NIT), which showed much higher hydration activity than hydrolysis activity, was designed for efficient hydrolysis of 2-CN.

Atypical endometrial hyperplasia in a 35-year-old woman: A case report and literature review.

Background: Atypical endometrial hyperplasia (AEH) is a common precancerous lesion of endometrial carcinoma (EC). The risk factors for AEH and EC directly or indirectly related to estrogen exposure include early menarche, nulliparity, polycystic ovarian syndrome, diabetes, and obesity. Both AEH and EC rarely occur in young patients (< 40-years-old), who may desire to maintain their fertility.

Recent advancements in enzyme engineering via site-specific incorporation of unnatural amino acids.

With increased attention to excellent biocatalysts, evolving methods based on nature or unnatural amino acid (UAAs) mutagenesis have become an important part of enzyme engineering. The emergence of powerful method through expanding the genetic code allows to incorporate UAAs with unique chemical functionalities into proteins, endowing proteins with more structural and functional features. To date, over 200 diverse UAAs have been incorporated site-specifically into proteins via this methodology and many of them have been widely exploited in the field of enzyme engineering, making this genetic code expansion approach possible to be a promising tool for modulating the properties of enzymes.

Efficient strategies to enhance plasmid stability for fermentation of recombinant Escherichia coli harboring tyrosine phenol lyase.

Objective: To solve the bottleneck of plasmid instability during microbial fermentation of L-DOPA with recombinant Escherichia coli expressing heterologous tyrosine phenol lyase.

Results: The tyrosine phenol lyase from Fusobacterium nucleatum was constitutively expressed in E. coli and a fed-batch fermentation process with temperature down-shift cultivation was performed.

Purification and Biochemical Characterization of a Tyrosine Phenol-lyase from Morganella morganii.

Tyrosine phenol-lyase (TPL) is a valuable and cost-effective biocatalyst for the biosynthesis of L-tyrosine and its derivatives, which are valuable intermediates in the pharmaceutical industry. A TPL from Morganella morganii (Mm-TPL) was overexpressed in Escherichia coli and characterized. Mm-TPL was determined as a homotetramer with molecular weight of 52 kDa per subunit.

Regulation of homoserine O-succinyltransferase for efficient production of L-methionine in engineered Escherichia coli.

l-Methionine biosynthesis in Eschericha coli consists of multiple unit modules with various enzymes involved and the imbalance between different modules always restricted its productivity. In this study, the key enzymes participating in the pathway were investigated for their effect on l-methionine production and the pivotal enzyme homoserine O-succinyltransferase (MetA) was designed to be regulated. The surface amino acid residues of MetA were effectively modified through site-saturation mutagenesis and single mutants L63F, A28V, P298L and double mutant L63F/A28V were obtained with improved l-methionine productivity.

Enhanced production of L-methionine in engineered Escherichia coli with efficient supply of one carbon unit.

Objective: L-methionine is an important sulfur-containing amino acid essential for humans and animals. Its biosynthesis pathway is complex and highly regulated. This study aims to explore the bottleneck limiting the improvement of L-methionine productivity and apply efficient strategies to increase L-methionine production in engineered E.

Development of a robust nitrilase by fragment swapping and semi-rational design for efficient biosynthesis of pregabalin precursor.

Protein engineering is a powerful tool for improving the properties of enzymes. However, large changes in enzyme properties are still challenging for traditional evolution strategies because they usually require multiple amino acid substitutions. In this study, a feasible evolution approach by a combination of fragment swapping and semi-rational design was developed for the engineering of nitrilase.

Genetic Engineering Approaches Used to Increase Lipid Production and Alter Lipid Profile in Microbes.

Microbial production of lipids provides important alternative sources for a variety of fine chemicals and fuels. With the development of biotechnology, genetic engineering approaches are widely used to increase lipid production in microbes, as well as to alter the lipid profile with unique physicochemical properties. In this chapter, based on the well-known information of de novo lipid accumulation mechanisms in microbes, genetic engineering strategies at the direction of increased supply of substrates, regulation of lipid synthesis pathway, regulation of lipid catabolic pathway, and regulation of lipid profiles are described.

Highly regio- and enantioselective synthesis of chiral intermediate for pregabalin using one-pot bienzymatic cascade of nitrilase and amidase.

Nitrilase-mediated hydrolysis of isobutylsuccinonitrile (IBSN) is a highly attractive approach for (S)-3-cyano-5-methylhexanoic acid ((S)-CMHA), the critical chiral intermediate of pregabalin. In this study, a robust nitrilase from Arabis alpina (AaNIT) was screened and engineered. The N258D mutant was obtained with high catalytic activity and excellent enantioselectivity (E > 300) towards IBSN at a high substrate concentration of 100 g L.

Efficient biosynthesis of (R)-3-amino-1-butanol by a novel (R)-selective transaminase from Actinobacteria sp.

(R)-3-amino-1-butanol is a key intermediate of Dolutegravir for the treatment of HIV/AIDS and its green and efficient biosynthesis has attracted a great deal of attention. Transaminases are currently used as promising biocatalyst for the synthesis of chiral amines. However, many transaminases have (S)-specificity and (R)-selective transaminases were less exploited and studied, making the production of (R)-amines remain challenging.

Statistical medium optimization and DO-STAT fed-batch fermentation for enhanced production of tyrosine phenol lyase in recombinant Escherichia coli.

Tyrosine phenol lyase (TPL) is a robust biocatalyst for the production of L-dihydroxyphenylalanine (L-DOPA). The improvement of TPL production is conducive to the industrial potential. In this study, the optimization of culture medium of recombinant Escherichia coli harboring TPL from Fusobacterium nucleatum (Fn-TPL) was carried out.

Structure-Based Engineering of Amidase from sp. for Efficient 2-Chloronicotinic Acid Biosynthesis.

2-Chloronicotinic acid is a key intermediate of pharmaceuticals and pesticides. Amidase-catalyzed hydrolysis provides a promising enzymatic method for 2-chloronicotinic acid production from 2-chloronicotinamide. However, biocatalytic hydrolysis of 2-chloronicotinamide is difficult due to the strong steric and electronic effect caused by 2-position chlorine substituent of the pyridine ring.

Continuous production of aprepitant chiral intermediate by immobilized amidase in a packed bed bioreactor.

To develop a highly efficient method for aprepitant chiral intermediate (S)-4-fluorophenylglycine, a continuous reaction system was established in packed bed bioreactor using amidase covalently immobilized on epoxy resin as biocatalyst. The epoxy resin was firstly modified by metal-chelate method and functional groups (Cu-IDA) generated were able to rapidly adsorb amidases, which were further covalently bound onto the modified resin with 90.1% immobilization yield and 80.

Efficient Biocatalytic Synthesis of Chiral Intermediate of Pregabalin Using Immobilized Lipase.

A mutant L206F/P207F/L259F of lipase (TTL) exhibited high hydrolytic activity towards 2-carboxyethyl-3-cyano-5-methylhexanoic acid ethyl ester (CNDE) for synthesis of ()-2-carboxyethyl-3-cyano-5-methylhexanoic acid (-CCMA), a key chiral intermediate of pregabalin. However, low conversion at high CNDE concentration and unreusability of the free TTL mutant restricted its industrial applications. In this study, the TTL mutant was immobilized onto epoxy resin and its catalytic properties for kinetic resolution of CNDE were investigated.

Identification and engineering of the key residues at the crevice-like binding site of lipases responsible for activity and substrate specificity.

Objective: Rational engineering of the crevice-like binding site of lipases for improvement of lipases' catalytic properties.

Resuts: The residues located at the crevice-like binding site of four representative lipases including Thermomyces lanuginosus lipases (TLL and Lip), Rhizopus oryzae lipase (ROL), and Rhizomucor miehei lipase (RML) were identified through structural analysis. The residues at the bottom of the crevice-like binding site recognizing the substrates with short/medium carbon chain length and those located at the right-hand wall of the surface crevice region affecting the product release were changed by site-directed mutagenesis.

An efficient colorimetric high-throughput screening method for synthetic activity of tyrosine phenol-lyase.

Tyrosine phenol-lyase (TPL) naturally catalyzes the reversible β-elimination of l-tyrosine to phenol, pyruvate and ammonium. With its reverse reaction (synthetic activity), l-tyrosine and its derivatives could be synthesized with high atom economy, which are widely used in pharmaceutical industries. In this study, a high-throughput screening method for synthetic activity of TPL was developed.

Efficient chemoenzymatic synthesis of (S)-α-amino-4-fluorobenzeneacetic acid using immobilized penicillin amidase.

An efficient chemoenzymatic route was developed for synthesis of (S)-α-amino-4-fluorobenzeneacetic acid, a valuable chiral intermediate of Aprepitant, using immobilized penicillin amidase catalyzed kinetic resolution of racemic N-phenylacetyl-4-fluorophenylglycine. The optimum temperature, pH and agitation rate of the reaction were determined to be 40 °C, 9.5 and 300 rpm, respectively.