RESUMO
(R)-N-(2,6-dimethylphenyl) aminopropionic acid methyl ester ((R)-DMPM) is an important chiral intermediate of the fungicide N-(2,6-Dimethylphenyl)-N-(methoxyacetyl)-alanine methyl ester ((R)-Metalaxyl). In this study, (1) D3520 (macroporous acrylic anion resin), selected from the ten resins, was used to immobilize the esterase from Pseudochrobactrum asaccharolyticum WZZ003 (PAE07) for resoluting the (R,S)-DMPM to obtain (R)-DMPM. (2) Up to 20 g/L PAE07 could be immobilized onto D3520 with a high enzymatic activity of 32.4 U/g. Moreover, the Km and Vmax values of 19.1 mM and 2.8 mM/min for D3520-immobilized PAE07 indicated its high activity and stereoselectivity. (3) The optimal temperature and pH for the immobilized PAE07 were 40 â and 8.0, and substrate concentration was up to 0.35 M. After 15 h reaction, the conversion rate from (R,S)-DMPM to (R)-DMPM was 48.0% and the e.e.p and E values were 99.5% and 1393.0, respectively. In scale-up resolution, 200 g/L substrate and 12.5 g immobilized esterase PAE07 condition, a conversion rate from substrate to product of 48.1% and a product e.e.p of 98% were obtained within 12 h, with the activity of immobilized PAE07 retained 80.2% after 5 cycles of reactions. These results indicated that the D3520-immobilized esterase PAE07 had great potential for enzymatic resolution of (R,S)-DMPM to prepare (R)-Metalaxyl.
Assuntos
Enzimas Imobilizadas , Esterases , Estereoisomerismo , TemperaturaRESUMO
d-pantolactone is an intermediate in the synthesis of d-pantothenic acid, which is known as vitamin B5. The commercial synthesis of d-pantolactone is carried out through the selective resolution of dl-pantolactone catalyzed by lactone hydrolase. In contrast to a kinetic resolution approach, the deracemization of dl-pantolactone is a simpler, greener, and more sustainable way to obtain d-pantolactone with high optical purity. Herein, an efficient three-enzyme cascade was developed for the deracemization of dl-pantolactone, using l-pantolactone dehydrogenase from Amycolatopsis methanolica (AmeLPLDH), conjugated polyketone reductase from Zygosaccharomyces parabailii (ZpaCPR), and glucose dehydrogenase from Bacillus subtilis (BsGDH). The AmeLPLDH was used to catalyze the dehydrogenated l-pantolactone into ketopantolactone; the ZpaCPR was used to further catalyze the ketopantolactone into d-pantolactone; and glucose dehydrogenase together with glucose fulfilled the function of coenzyme regeneration. All three enzymes were co-expressed in E. coli strain BL21(DE3), which served as the whole-cell biocatalyst. Under optimized conditions, 36 h deracemization of 1.25 M dl-pantolactone d-pantolactone led to an e.e.p value of 98.6%, corresponding to productivity of 107.7 g/(l·d).
Assuntos
4-Butirolactona , Escherichia coli , Glucose 1-DesidrogenaseRESUMO
A gene encoding an esterase from Bacillus aryabhattai (BaCE) was identified, synthesized and efficiently expressed in the Escherichia coli system. A semi-rational protein engineering was applied to further improve the enzyme's enantioselectivity. Under the guidance of the molecular docking result, a single mutant BaCE-L86Q and a double mutant BaCE-L86Q/G284E were obtained, with its Emax value 6.4 times and 13.9 times of the wild-type BaCE, respectively. The recombinant BaCEs were purified and characterized. The overwhelming E value demonstrated that BaCE-L86Q/G284E was a promising biocatalyst for the biological resolution to prepare (S)-indoline-2-carboxylic acid.
Assuntos
Ácidos Carboxílicos , Esterases , Bacillus , Escherichia coli/genética , Escherichia coli/metabolismo , Esterases/metabolismo , Indóis , Simulação de Acoplamento Molecular , Engenharia de ProteínasRESUMO
Chitin, the second richest polymer in nature, is composed of the monomer N-acetylglucosamine (GlcNAc), which has numerous functions and is widely applied in the medical, food, and chemical industries. However, due to the highly crystalline configuration and low accessibility in water of the chitin resources, such as shrimp and crab shells, the chitin is difficult utilize, and the traditional chemical method causes serious environment pollution and a waste of resources. In the present study, three genes encoding chitinolytic enzymes, including the N-acetylglucosaminidase from Ostrinia furnacalis (OfHex1), endo-chitinase from Trichoderma viride (TvChi1), and multifunctional chitinase from Chitinolyticbacter meiyuanensis (CmChi1), were expressed in the Pichia pastoris system, and the positive transformants with multiple copies were isolated by the PTVA (post-transformational vector amplification) method, respectively. The three recombinants OfHex1, TvChi1, and CmChi1 were induced by methanol and purified by the chitin affinity adsorption method. The purified recombinants OfHex1 and TvChi1 were characterized, and they were further used together for degrading chitin from shrimp and crab shells to produce GlcNAc through liquid-assisted grinding (LAG) under a water-less condition. The substrate chitin concentration reached up to 300 g/L, and the highest yield of the product GlcNAc reached up to 61.3 g/L using the mechano-enzymatic method. A yield rate of up to 102.2 g GlcNAc per 1 g enzyme was obtained.
Assuntos
Quitina , Quitinases , Acetilglucosamina/metabolismo , Animais , Quitina/química , Quitinases/química , Crustáceos/metabolismo , ÁguaRESUMO
Brivaracetam is a structural derivative of the chiral drug levetiracetam and has been approved for the adjuvant treatment of partial epilepsy. As a new antiepileptic drug, it is widely used in a variety of epilepsy models. In this study, a novel lipase M16 derived from Aspergillus oryzae WZ007 was cloned, expressed, and used for chiral resolution. Lipase M16 has a high enantioselectivity to the racemic substrate (R,S)-methyl 2-propylsuccinate 4-tert-butyl ester, and the intermediate (R)-2-propylsuccinic acid 4-tert-butyl ester of brivaracetam was obtained efficiently. Under optimal conditions, the enantiomeric excess of substrate was up to 99.26%, and the e.e.p was 96.23%. The conversion and apparent E value were 50.63% and 342.48, respectively. This study suggests a new biocatalytic resolution via lipase M16 for preparing the brivaracetam chiral intermediate and its potential application in the pharmaceutical industry.
Assuntos
Aspergillus oryzae/enzimologia , Biocatálise , Lipase/metabolismo , Pirrolidinonas/metabolismo , Esterificação , Cinética , EstereoisomerismoRESUMO
In this study, a novel lipase M5 derived from Aspergillus oryzae WZ007 was prone to exhibit high hydrolytic activity and stereoselectivity towards racemic substrate (R,S)-ethyl 2-bromoisovalerate. (R)-ethyl 2-bromoisovalerate was obtained by enzymatic resolution, which is the key chiral intermediate for highly efficient enantiomerically fluvalinate. The results showed that the enzymatic reaction was carried out in 120mM racemic substrate for 3 hours, the enantiomeric excess reached 98.6%, the conversion was 51.7%, and E value above 120. Therefore, the novel lipase M5 has the ability to efficiently produce (R)-ethyl 2-bromoisovalerate, which greatly reduces the industrial production cost of the highly efficient counterpart of fluvalinate.
Assuntos
Aspergillus oryzae/enzimologia , Biocatálise , Lipase/metabolismo , Ácidos Pentanoicos/química , Ácidos Pentanoicos/isolamento & purificação , Concentração de Íons de Hidrogênio , Cinética , Ácidos Pentanoicos/metabolismo , Solventes/química , Estereoisomerismo , Especificidade por Substrato , TemperaturaRESUMO
A novel enzyme immobilization method employing metal-organic framework (MOF) encapsulation and macroporous resin adsorption was developed in this study. Candida antarctica lipase B (CALB) was firstly encapsulated onto metal-organic frame structures (Zeolitic imidazole framework-8, ZIF-8) and further bonded to macroporous resin by physical adsorption. Under optimized immobilization conditions, the activity of the prepared immobilized lipase (CALB-ZIF-8@D101) determined via the methyl esterification of oleic acid was 38.4 U/mg. Compared with free lipase, the immobilized lipase exhibited improved thermal and operational stability and organic solvent tolerance. These results demonstrate that the immobilization method of ZIF-8 encapsulation and macroporous resin adsorption enhanced enzyme properties at a superior level.
Assuntos
Enzimas Imobilizadas/metabolismo , Proteínas Fúngicas/metabolismo , Imidazóis/química , Lipase/metabolismo , Adsorção , Estabilidade Enzimática , Tamanho da Partícula , Zeolitas/químicaRESUMO
Aspergillus oryzae lipase (AOL) is a potential biocatalyst for industrial application. In this study, a mutant lipase AOL-3F38N/V230R was screened through two rounds of directed evolution, resulting in a fourfold increase in lipase activity, and threefold in catalytic efficiency (kcat/Km), while maintaining its excellent stereoselectivity. AOL-3F38N/V230R enzyme activity was maximum at pH 7.5 and also at 40 °C. And compared with wild-type AOL-3, AOL-3F38N/V230R preferentially hydrolyzed the fatty acid ethyl ester carbon chain length from C4 to C6-C10. In the same catalytic reaction conditions, the conversion of (R,S)-ethyl-2-(4-hydroxyphenoxy) propanoate ((R,S)-EHPP) by AOL-3F38N/V230R can be increased 169.7% compared to the original enzyme. The e.e.s of (R,S)-EHPP achieved 99.4% and conversion about 50.2% with E value being 829.0. Therefore, AOL-3F38N/V230R was a potential biocatalyst for obtaining key chiral compounds for aryloxyphenoxy propionate (APP) herbicides.
Assuntos
Aspergillus oryzae/enzimologia , Lipase/química , Propionatos/química , Biocatálise , Catálise , Células Imobilizadas/metabolismo , Evolução Molecular Direcionada , Eletroforese em Gel de Poliacrilamida , Esterificação , Ésteres , Biblioteca Gênica , Concentração de Íons de Hidrogênio , Hidrólise , Íons , Cinética , Simulação de Acoplamento Molecular , Mutagênese Sítio-Dirigida , Mutação , Engenharia de Proteínas , Solventes/química , Estereoisomerismo , TemperaturaRESUMO
Pichia pastoris expression is a mature and efficient eukaryotic expression system. In this work, Aspergillus oryzae lipase (AOL, with the molecular mass of 28â¯kDa), which can perform highly stereoselective hydrolysis of (R, S)-methyl 2-(4-hydroxyphenoxy) propanoate, was expressed in P. pastoris X-33. The specific activity of AOL was 432 U/mg, which was obtained by fed-batch cultivation in a 5â¯L bioreactor using a methanol feeding strategy. After fermentation, the supernatant was concentrated by ultrafiltration with a 10â¯kDa cut-off membrane and purified with DEAE-Sepharose™ FF ion-exchange chromatography and phenyl Seflnose™ 6 FF hydrophobic interaction chromatography. The purified lipase activity reached 5509 U/mg. AOL showed high activity toward short-chain triacylglyceride (C4), and the optimum temperature and pH were 40⯰C and 8.0, respectively. The purified enzyme activity was inhibited by Zn2+ and Cu2+. Moreover, the Km and Vmax values were 1â¯mM and 32.89â¯mmol/min, respectively.
Assuntos
Aspergillus oryzae/enzimologia , Lipase/genética , Pichia/genética , Aspergillus oryzae/genética , Aspergillus oryzae/metabolismo , Clonagem Molecular/métodos , Expressão Gênica , Lipase/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Estereoisomerismo , Especificidade por Substrato , Temperatura , Triglicerídeos/química , Triglicerídeos/metabolismoRESUMO
In this study, a newly isolated strain screened from the indoxacarb-rich agricultural soils, Bacillus cereus WZZ006, has a high stereoselectivity to racemic substrate 5-chloro-1-oxo-2,3-dihydro-2-hydroxy-1H-indene-2-carboxylic acid methyl ester. (S)-5-chloro-1-oxo-2,3-dihydro-2-hydroxy-1H-indene-2-carboxylic acid methyl ester was obtained by bio-enzymatic resolution. After the 36-hour hydrolysis in 50-mM racemic substrate under the optimized reaction conditions, the e.e.s was up to 93.0% and the conversion was nearly 53.0% with the E being 35.0. Therefore, B cereus WZZ006 performed high-level ability to produce (S)-5-chloro-1-oxo-2,3-dihydro-2-hydroxy-1H-indene-2-carboxylic acid methyl ester. This study demonstrates a new biocatalytic process route for preparing the indoxacarb chiral intermediates and provides a theoretical basis for the application of new insecticides in agricultural production.
Assuntos
Bacillus cereus/citologia , Bacillus cereus/metabolismo , Biocatálise , Indenos/metabolismo , Oxazinas/metabolismo , Bacillus cereus/enzimologia , Hidrolases de Éster Carboxílico/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Indenos/química , Cinética , Rotação , Microbiologia do Solo , Solventes/química , Estereoisomerismo , TemperaturaRESUMO
OBJECTIVE: To purify an esterase which can selectively hydrolyze (R,S)-ethyl indoline-2-carboxylate to produce (S)-indoline-2-carboxylic acid and characterize its enzymatic properties. RESULTS: An intracellular esterase from Bacillus aryabhattai B8W22 was isolated and the purified protein was identified as a carboxylesterase by MALDI-TOF mass spectrometry. The enzyme (named BaCE) was 59.03-fold purification determined to be of approximately 35 kDa. Its specific activity was 0.574 U/mL with 20% yield. The enzyme showed maximum activity at pH 8.5 and 30 °C and was stable at 20-30 °C using pNPB as the substrate. The Km, Vmax, kcat and kcat/Km of the esterase were 0.52 mM, 6.39 µM/min, 26.87 min-1 and 51.67 mM/min, respectively. The esterase demonstrated high enantioselectivity toward (S)-ethyl indoline-2-carboxylate with 96.55% e.e.p at 44.39% conversion, corresponding to an E value of 133.45. CONCLUSIONS: In this study, a new esterase BaCE with an apparent molecular mass of 35 kDa was purified to homogeneity for the first time. The esterase from Bacillus aryabhattai B8W22 was isolated with a purification more than 59-fold and a yield of 20% by anion exchange chromatography and hydrophobic interaction chromatography. And its biochemical characterization were described in detail with pNPB as substrate. It displayed high enantioselectivity toward (S)-ethyl indoline-2-carboxylate. We next plan to highly express esterase BaCE in Escherichia coli, and apply it to industrial production of (S)-indoline-2-carboxylic acid.
Assuntos
Bacillus/enzimologia , Esterases/isolamento & purificação , Esterases/metabolismo , Indóis/metabolismo , Biotransformação , Estabilidade Enzimática , Esterases/química , Concentração de Íons de Hidrogênio , Cinética , Peso Molecular , Especificidade por Substrato , TemperaturaRESUMO
PURPOSE: We conducted a cross-sectional investigation of health-related quality of life (HRQOL) among maintenance haemodialysis (MHD) patients, and determined important predictive factors of HRQOL in these patients. METHODS: Psychological factors were evaluated with the Hospital Anxiety and Depression Scale (HADS), the Pittsburgh Sleep Quality Index (PSQI) and the General Self-Efficacy Scale (GSES). HRQOL was evaluated with the EQ-5D. Laboratory data (albumin, haemoglobin and C-reactive protein) were collected for medical evaluation. We also collected participants' demographic data, including gender, age, et al. This study was in compliance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist. RESULTS: The mean EQ-5D score was 0.86 ± 0.12, mean HADS-anxiety score was 5.27 ± 3.41, mean HADS-depression score was 5.29 ± 3.58, mean PSQI score was 7.00 ± 4.23 and mean GSES score was 6.86 ± 2.03. Participants' mean haemoglobin was 108.18 ± 16.45 g/L, mean albumin was 41.80 ± 4.61 g/L and mean C-reactive protein was 8.88 ± 18.50 mg/L. HRQOL was negatively correlated with HADS-anxiety (r = -0.390, p < 0.001), HADS-depression (r = -0.385, p < 0.001), PSQI (r = -0.285, p < 0.001) and C-reactive protein (r = -0.198, p = 0.034). HRQOL was positively correlated with GSES (r = 0.205, p = 0.007). Age (p < 0.001), anxiety (p < 0.001), depression (p = 0.002), and postdialysis unemployment (p < 0.001) were independent risk factors for HRQOL. CONCLUSION: Different health interventions should be implemented to improve patients' HRQOL. RELEVANCE TO CLINICAL PRACTICE: The results will provide evidence for establishing healthcare interventions to maintain or improve HRQOL among this patient population.
Assuntos
Qualidade de Vida , Diálise Renal/psicologia , Adulto , Idoso , Ansiedade/diagnóstico , Ansiedade/psicologia , Estudos Transversais , Depressão/diagnóstico , Depressão/psicologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Inquéritos e Questionários , Adulto JovemRESUMO
This study describes a sensitive and fluorescent microplate assay method to detect lipase transesterification activity. Lipase-catalyzed transesterification between butyryl 4-methyl umbelliferone (Bu-4-Mu) and methanol in tert-butanol was selected as the model reaction. The release of 4-methylumbelliferone (4-Mu) in the reaction was determined by detecting the fluorescence intensity at λex 330â¯nm and λem 390â¯nm. Several lipases were used to investigate the accuracy and efficiency of the proposed method. Apparent Michaelis constant (Km) was calculated for transesterification between Bu-4-Mu and methanol by the lipases. The main advantages of the assay method include high sensitivity, inexpensive reagents, and simple detection process.
Assuntos
Lipase/química , Esterificação , Espectrometria de Fluorescência/métodosRESUMO
More than 30% of the registered pesticides are chiral with one or more chiral centers and exist as two or more enantiomers. The frequency of chiral chemicals and their environmental safety has been considered in their risk assessment in recent decades. Despite the fact that metabolic disturbance is an important sensitive molecular initiating event of toxicology effects, the potential mechanisms of how chiral compounds affect metabolism phenotypes in organisms remain unclear. As a typical chiral pesticide, metalaxyl is an acylalanine fungicide with systemic function. Although the fungicidal activity almost comes from the R-enantiomer, the toxicity of both enantiomers in animals and human beings is not yet clear. In this study, a nuclear magnetic resonance (NMR)-based metabolomics approach was adopted to evaluate the enantioselectivity in metabolic perturbations in adolescent rats. On the basis of multivariate statistical results, stable and evident metabolic profiles of the enantiomers were obtained. When rats were exposed to R-metalaxyl, the significantly perturbed metabolic pathways were biosynthesis of valine, leucine, and isoleucine, synthesis and degradation of ketone bodies, and metabolism of glycerolipid. In contrast, more significantly perturbed metabolic pathways were obtained when the rats were exposed to S-metalaxyl, including glycolysis, biosynthesis of valine, leucine, and isoleucine, metabolism of glycine, serine, and threonine, synthesis and degradation of ketone bodies, metabolism of glycerophospholipid and glycerolipid. These abnormal metabolic pathways were closely related to liver metabolism. These results offer more detailed information about the enantioselective metabolic effects of metalaxyl in adolescent development and provide data for the health risk assessment of metalaxyl at molecular level.
Assuntos
Fungicidas Industriais , Poluentes do Solo , Alanina/análogos & derivados , Animais , Biodegradação Ambiental , Humanos , Espectroscopia de Ressonância Magnética , Metaboloma , Metabolômica , Ratos , EstereoisomerismoRESUMO
The kinetic resolution of (R,S)-1-(4-chlorophenyl)ethylamine was accomplished using a commercial lipase from Candida antarctica (Novozym 435). The performance of this lipase was investigated for the enantioselective amidation of (R,S)-1-(4-chlorophenyl)ethylamine, leaving the target product (S)-1-(4-chlorophenyl)ethylamine in its unreacted form. The effects of various types of solvents and an acyl donor, the molar ratio of the substrate to the acyl donor, and the reaction temperature were studied. The optimum reaction conditions were found to result in amidation with methyl 2-tetrahydrofuroate at 40°C in methyl tert-butyl ether, with a substrate/acyl donor molar ratio of 1:2.4. The conversion rate of (R,S)-1-(4-chlorophenyl)ethylamine was 52%, with an enantiomeric excess of 99% towards the unreacted substrate in a reaction time of 22 hours. Finally, using optically pure (S)-1-(4-chlorophenyl)ethylamine as the raw material, the chemical synthesis of (S)-N-(1-(4-chlorphenyl)ethyl)-2-(5,7-dimethyl-[1,2,4]triazolo[1,5-a]pyrimidin-2-ylthio)acetamide, a novel triazolopyrimidine herbicide, was achieved, and the total yield and purity were 83.5% and 95.3%, respectively.
RESUMO
D-alanine is widely used in medicine, food, additives, cosmetics, and other consumer items. Esterase derived from Bacillus cereus WZZ001 exhibits high hydrolytic activity and stereoselectivity. In this study, we expressed the esterase gene in Escherichia coli BL21 (DE3). We analyzed the biocatalytic resolution of N-acetyl-DL-alanine methyl ester by immobilized whole E. coli BL21 (DE3) cells, which were prepared through embedding and cross-linking. We analyzed biocatalytic resolution under the optimal conditions of pH of 7.0, temperature of 40°C and substrate concentration of at 700 mM with an enantiomeric excess of 99.99% and e.e.p of 99.50%. The immobilized recombinant B. cereus esterase E. coli BL21 (DE3) cells exhibited excellent reusability and retained 86.04% of their initial activity after 15 cycles of repeated reactions. The immobilized cells are efficient and stable biocatalysts for the preparation of N-acetyl-D-alanine methyl esters.
Assuntos
Alanina/análogos & derivados , Escherichia coli/genética , Esterases/metabolismo , Alanina/química , Alanina/metabolismo , Bacillus cereus/genética , Catálise , Células Imobilizadas , Esterases/genética , Concentração de Íons de Hidrogênio , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Estereoisomerismo , TemperaturaRESUMO
Enantioselectivity of chiral pesticides in environmental safety has attracted more and more attention. In this study, we evaluated the enantioselective toxicity of rac-metalaxyl and R-metalaxyl to zebrafish (Danio rerio) embryos through various malformations including pericardial edema, yolk sac edema, crooked body, and short tails. The results showed that there were significant differences in toxicity to zebrafish embryos caused by rac-metalaxyl and R-metalaxyl, and the LC50 s at 96 h are 416.41 (353.91, 499.29) mg · L(-1) and 320.650 (279.80, 363.46) mg · L(-1) , respectively. In order to explore the possible mechanism of the development defects, the genes involved in the hypothalamic-pituitary-gonadal axis (vtg1, vtg2, cyp17, cyp19a, cyp19b) and hypothalamic-pituitary-thyroid axis (dio1, dio2, nis, tg, tpo) were quantified by quantitative real-time polymerase chain reaction (qRT-PCR). The results revealed that there were no significant differences in the expression of vtg1, vtg2, cyp17, cyp19a, and cyp19b after exposure to rac-metalaxyl. However, the expression of vtg1, cyp19a, and cyp19b decreased significantly after exposure to R-metalaxyl. And likewise, rac-metalaxyl only caused the upregulation of dio2, while R-metalaxyl suppressed the expression of dio1 and tpo and induced the expression of dio2 and nis. The change of gene expression may cause the enantioselectivity in developmental toxicity in zebrafish embryo. The data provided here will be helpful for us to comprehensively understand the potential ecological risks of the currently used chiral fungicides. Chirality 28:489-494, 2016. © 2016 Wiley Periodicals, Inc.
Assuntos
Alanina/análogos & derivados , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Peixe-Zebra/embriologia , Alanina/química , Alanina/toxicidade , Animais , Embrião não Mamífero/efeitos dos fármacos , Praguicidas/química , Praguicidas/toxicidade , Estereoisomerismo , Peixe-Zebra/genéticaRESUMO
A sensitive and practical high-throughput screening method for assaying lipase synthetic activity is described. Lipase-catalyzed transesterification between vinyl acetate and n-butanol in n-hexane was chosen as a model reaction. The released acetaldehyde was determined by the colorimetric method using 3-methyl-2-benzothialinone (MBTH) derivatization. In comparison with other methods, the major advantages of this process include high sensitivity, simple detection, inexpensive reagents, and low requirements for instruments.
Assuntos
Colorimetria/métodos , Ensaios Enzimáticos/métodos , Lipase/metabolismo , Butanóis/metabolismo , Ensaios de Triagem em Larga Escala , Compostos de Vinila/metabolismoRESUMO
Rhodococcus erythropolis WZ010 was capable of producing optically pure (2S,3S)-2,3-butanediol in alcoholic fermentation. The gene encoding an acetoin(diacetyl) reductase from R. erythropolis WZ010 (ReADR) was cloned, overexpressed in Escherichia coli, and subsequently purified by Ni-affinity chromatography. ReADR in the native form appeared to be a homodimer with a calculated subunit size of 26,864, belonging to the family of the short-chain dehydrogenase/reductases. The enzyme accepted a broad range of substrates including aliphatic and aryl alcohols, aldehydes, and ketones. It exhibited remarkable tolerance to dimethyl sulfoxide (DMSO) and retained 53.6 % of the initial activity after 4 h incubation with 30 % (v/v) DMSO. The enzyme displayed absolute stereospecificity in the reduction of diacetyl to (2S,3S)-2,3-butanediol via (S)-acetoin. The optimal pH and temperature for diacetyl reduction were pH 7.0 and 30 °C, whereas those for (2S,3S)-2,3-butanediol oxidation were pH 9.5 and 25 °C. Under the optimized conditions, the activity of diacetyl reduction was 11.9-fold higher than that of (2S,3S)-2,3-butanediol oxidation. Kinetic parameters of the enzyme showed lower K(m) values and higher catalytic efficiency for diacetyl and NADH in comparison to those for (2S,3S)-2,3-butanediol and NADâº, suggesting its physiological role in favor of (2S,3S)-2,3-butanediol formation. Interestingly, the enzyme showed higher catalytic efficiency for (S)-1-phenylethanol oxidation than that for acetophenone reduction. ReADR-catalyzed asymmetric reduction of diacetyl was coupled with stereoselective oxidation of 1-phenylethanol, which simultaneously formed both (2S,3S)-2,3-butanediol and (R)-1-phenylethanol in great conversions and enantiomeric excess values.
Assuntos
Acetoína Desidrogenase/metabolismo , Butileno Glicóis/metabolismo , Rhodococcus/enzimologia , Acetoína Desidrogenase/química , Acetoína Desidrogenase/genética , Acetoína Desidrogenase/isolamento & purificação , Cromatografia de Afinidade , Clonagem Molecular , DNA Bacteriano/química , DNA Bacteriano/genética , Estabilidade Enzimática , Escherichia coli/genética , Expressão Gênica , Concentração de Íons de Hidrogênio , Cinética , Dados de Sequência Molecular , Peso Molecular , Multimerização Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Rhodococcus/genética , Análise de Sequência de DNA , Estereoisomerismo , Especificidade por Substrato , TemperaturaRESUMO
OBJECTIVE: To explore the clinical significance of negative fluid balance and infection management in the treatment of acute respiratory distress syndrome (ARDS) caused by severe novel coronavirus infection. METHODS: A retrospective survey was conducted. Patients with ARDS caused by severe novel coronavirus infection who were hospitalized in the department of critical care medicine of the Third Affiliated Hospital of Gansu University of Chinese Medicine and received non-invasive ventilator assisted ventilation were selected as the research objects. The fluid intake and output of all patients were accurately counted every day, and the fluid intake of the next day was adjusted according to the output of the previous day. According to the fluid negative balance, and whether the hospital infection management measures were complied with during the treatment and inspection of the patients, 45 patients with a negative fluid balance of more than 200 mL/d and strict management of nosocomial infection were taken as the observation group, and 48 patients with a negative fluid balance of less than 200 mL/d and no strict management of nosocomial infection were taken as the control group. The general data, weaning success rate, endotracheal intubation rate, mortality, as well as laboratory indicators such as white blood cell count (WBC), procalcitonin (PCT), C-reactive protein (CRP) after treatment were compared between the two groups. RESULTS: There were no significant differences in gender (male: 51.1% vs. 52.1%), age (years old: 66.31±15.92 vs. 67.50±13.59), acute physiology and chronic health evaluation II (APACHE II: 18.98±4.81 vs. 18.54±4.35) between the observation group and the control group (all P > 0.05), indicating that the baseline data were balanced and comparable. Compared with the control group, the weaning success rate of the observation group significantly increased [53.3% (24/45) vs. 31.2% (15/48), P = 0.031], endotracheal intubation rate significantly decreased [22.2% (10/45) vs. 43.8% (21/48), P = 0.028], mortality significantly reduced [20.0% (9/45) vs. 41.7% (20/48), P = 0.024], laboratory indicators WBC, PCT and CRP levels were significantly reduced [WBC (×109/L): 8.085±4.136 vs. 16.898±7.733, CRP (mg/L): 82.827±52.680 vs. 150.679±74.625, PCT (µg/L): 3.142±2.323 vs. 7.539±5.939, all P < 0.01]. CONCLUSIONS: Fluid negative balance and infection management have significant clinical significance in the treatment of severe novel coronavirus infection with ARDS.