Molecular Catalysis
·
2024
·
IF 3.9
Yan-Fei Liang,Shuai Feng,Dan Wu,Meng Ma,Jin-Tao Ren,Qian Zhao,Wen-Yun Gao,Heng Li
1-Deoxy- D- xylulose-5-phosphate synthase (DXS) is the first rate-limiting enzyme in the 2-methyl- D- erythritol-4-phosphate (MEP) terpenoid biosynthetic pathway. To explore the active sites of the protein, we made a series of mutations to the key amino acid residues of Escherichia coli DXS including H49, R420, D427, and R478. The results show that several mutants including H49Q lose almost all their catalytic activity in DXP synthesis, but the double-point mutants H49QD427H and H49QD427 N recover 100 % activity of the wild type enzyme. The kinetic characterization displays that the affinity of the double-point mutants for pyruvate and D- glyceraldehyde-3-phosphate only slightly decreases. We also assessed impact of the mutation on the oxidative decarboxylation activity of all the mutants. Despite the fact that H49QD427H and H49QD427 N get back the full activity with regard to DXP synthesis, their oxidase activity remains unrestored. Furthermore, we assayed the acceptor substrate spectrum of the mutants and the results show that a large portion of them catalyzes ligation between pyruvate and nitrosobenzene to form N-phenyl-N-hydroxyacetamide, whereas R420D, R420F, and D427H exhibit activity in connection of pyruvate and benzaldehyde to afford phenylacetocarbinol (PAC), with the first two mutants yielding ( S )-PAC (yields 21 %-25 %, ee values 71–75 %) while D427H furnishing ( R )-PAC (yield 41 %, ee value 91 %), implying the key role of D427 for the acceptor substrate recognition and the stereoselectivity of the enzyme. It is worth noting that this is the first report of DXS mutants that can recognize benzaldehyde as an acceptor substrate and generate both enantiomers of PAC.
研究领域:
生物化学
·
分子生物学
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产品关联
DOI
高影响因子
TALANTA
·
2016
·
IF 4.035
Shu Min Lin,Shuo Geng,Na Li,Nian Bing Li,Hong Qun Luo
Mercury ion is one of the most hazardous metal pollutants that can cause deleterious effects on human health and the environment even at low concentrations. It is necessary to develop new mercury detection methods with high sensitivity, specificity and rapidity. In this study, a novel and green strategy for synthesizing D-penicillamine-capped copper nanoparticles (DPA-CuNPs) was successfully established by a chemical reduction method, in which D-penicillamine and ascorbic acid were used as stabilizing agent and reducing agent, respectively. The as-prepared DPA-CuNPs showed strong red fluorescence and had a large Stoke's shift (270 nm). Scanning electron microscopy, transmission electron microscopy , Fourier-transform infrared spectroscopy, fluorescence spectroscopy, and ultraviolet-visible spectrophotometry were utilized to elucidate the possible fluorescence mechanism, which could be aggregation-induced emission effect. Based on the phenomenon that trace mercury ion can disperse the aggregated DPA-CuNPs, resulting in great fluorescence quench of the system, a sensitive and selective assay for mercury ion in aqueous solution with the DPA-CuNPs was developed. Under optimum conditions, this assay can be applied to the quantification of Hg 2+ in the 1.0–30 μM concentration range and the detection limit (3σ/slope) is 32 nM. The method was successfully applied to determine Hg 2+ in real water samples.
研究领域:
分析化学
·
环境科学
·
材料科学
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产品关联
DOI
PubMed
高影响因子
BIOCATALYSIS AND BIOTRANSFORMATION
·
2016
·
IF 0.892
Wei Wei,Danping Qi,Mingming Diao,Lu Zhaoxin,Fengxia Lv,Haizhen Zhao
In this study, the synthesis of 3-O-β-D-galactopyranosyl-sn-glycerol (GG) was performed by the reverse hydrolysis of D-galactose and glycerol using β-galactosidase from Kluyveromyces lactis. Four process variables, reaction temperature (30.0–45.0 °C), reaction time (24–48 h), enzyme concentration (150.00–350.00 U/mL), and substrate molar ratio (glycerol:D-galactose, 7.5:12.5 mmol/mmol) were investigated and optimized via response surface methodology (RSM) for optimal GG synthesis. Both quadratic equations and the optimal reaction conditions were established. Results showed that the four variables, i.e., reaction temperature, reaction time, enzyme concentration, and substrate molar ratio had significant (p < 0.0001) effects on the synthesis of GG. The optimal reaction conditions were identified as 350.00 U/mL of β-galactosidase concentration and 8.65:1.00 of substrate molar concentration ratio (glycerol: D-galactose) at 39.8 °C and 48 h of reaction. Under these conditions, the GG concentration was 140.03 g/L and GG yield was 55.71%, which both were close to the predicted values (143.26 g/L and 56.73%). This finding proves the RSM to be a useful tool in optimizing process conditions for GG synthesis.
研究领域:
生物化学
·
食品科学
·
酶工程
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产品关联
DOI
高影响因子
ADVANCES IN POLYMER TECHNOLOGY
·
2018
·Vol. 37
·期 8
·3038-3044
·
IF 2.073
Wensheng Tan,Renjun Fu,Hong Ji,Datong Wu,Yueguo Xu,Yong Kong
Polyaniline (PANI) is chemically synthesized using two low-molecular-weight organic acids (D-tartaric acid and citric acid) as the dopants, respectively. The doped PANI is characterized by field emission scanning electron microscopy, FT-IR spectra, and X-ray diffraction. The two doped PANIs exhibit different electrochemical properties, especially in the supercapacitive behaviors. Compared with citric acid-doped PANI, D-tartaric acid-doped PANI shows higher specific capacitance (525 F/g at 1 A/g) and cyclic stability. The good electrochemical behaviors of D-tartaric acid-doped PANI might be attributed to the two carboxyl groups of D-tartaric acid, which are beneficial to the oriented growth of PANI chains. The results demonstrate that compared with citric acid, D-tartaric acid is a promising dopant for PANI used in supercapacitors.
研究领域:
材料科学
·
电化学
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产品关联
DOI
高影响因子
ANALYTICAL CHEMISTRY
·
2024
·
IF 6.7
Chang Liu,Yanan Wu,Mengying Li,Fang Liu,Pengfei Kong,Haifeng Yang,Xinling Liu
Salivary d-alanine (d-Ala) and d-proline (d-Pro) are of concern for their potential in the noninvasive diagnosis of gastric cancer (GC). Most reports have succeeded in determining the total concentration of d-Ala and d-Pro. However, for personalized diagnosis and better elucidation of the underlying specific correlation of d-Ala (or d-Pro) with GC, it is desirable to determine the specific concentration of d-Ala or d-Pro. Herein, we propose an enantiomer-specific tandem assay of d-Ala based on the colorimetric reaction between 2,4-dinitrophenylhydrazine and pyruvic acid generated from the deamination of d-Ala catalyzed by d-amino acid oxidase, which is easily distinguished from l-form amino acids, d-Pro, and many other species. A linear concentration range is established from 20 to 400 μmol/L with a limit of detection of 1.01 μmol/L. Real saliva sample tests reveal that the levels of d-Ala in GC cases are remarkably higher than those in healthy individuals, which offers a simple and low-cost strategy for GC diagnosis. Simultaneously, the total concentrations of d-Ala and d-Pro in saliva are determined. Hence, the concentration of d-Pro and the proportion of d-Ala could be calculated, which further provides more molecule- and individual-specific information. This research may offer a convenient method for noninvasive diagnosis of GC and pave a new route to explore the potentials of rare d-form amino acids in disease diagnosis and treatment.
研究领域:
生物化学
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医学诊断
·
癌症研究
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DOI
PubMed
高影响因子
RSC Advances
·
2014
·Vol. 4
·期 66
·34944-34949
·
IF 3.708
Jintao Lin,Shuangyue Li,Mingzhong Sun,Cuili Zhang,Wenbo Yang,Zehui Zhang,Xiaojie Li,Shao Li
The economical production of biodiesel from lignocellulose hydrolysates requires a robust D-xylose fermentation path. The present work found that Lipomyces starkeyi AS 2.1560 and Rhodosporidium toruloides AS 2.1389 could produce micro-lipid effectively from D-xylose solution by a two-stage culture mode. Results demonstrated that both L. starkeyi and R. toruloides could achieve high lipid production in xylose solution. High cell density fermentation was carried out by a feed-batch fermentation mode. After fermentation for 48 h in a bioreactor using unsterile xylose solution by L. starkeyi, the biomass, lipid and lipid content reached 97.4 g L−1, 63.9 g L−1, and 65.5%, respectively. Accordingly, the lipid productivity reached 1.3 g L−1 h−1 in the second stage. And the overall lipid productivity was 0.55 g L−1 h−1. Therefore, L. starkeyi and R. toruloides are highly effective D-xylose-fermenting oleaginous yeasts for lipid production in xylose solution. The two-stage culture method should provide a new opportunity to make the industrial production of biodiesel possible in the future.
研究领域:
微生物学
·
生物技术
·
可再生能源
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产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Chengwei Lu,Jun Han,Najun Li,Dongyun Chen,Qingfeng Xu,Hua Li,Jianmei Lu
Photocatalysis is a green and environmentally friendly method for degrading dangerous and nonbiodegradable pollutants. In this study, a sequence of metal-free triazine-based electronic donor–acceptor (D-A) conjugated polymers Tr-X (X = Th, BT, BTh) were prepared by D-A configuration regulation between triazine (Tr) and monomers containing N and S, such as thiophene (Th), bithiophene (BTh) and benzothiadiazole (BT) units, for the photocatalytic degradation of bisphenol A (BPA) and benzene contaminants in water under visible light. Among these, Tr-BTh exhibited complete photocatalytic degradation owing to its excellent D-A configuration. Moreover, the N and S atoms, which are rich in triazine and thiophene units, serve as highly dispersed reactive sites. The separation and transfer of photogenerated carriers can be further improved by expanding the light-absorption range of polymers. In addition, the polymers showed good adsorption for BPA and other aromatic organic pollutants through π-π interaction and surface hydrogen bonding, which provides a facile strategy for efficient polymer-based photocatalysts for water purification.
研究领域:
材料科学
·
环境科学
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产品关联
DOI
PubMed
高影响因子
Advanced Science
·
2023
·Vol. 11
·期 9
·2307173
·
IF 15.1
Jingzhi Yang,Yami Ran,Shaopeng Liu,Chenhao Ren,Yuntian Lou,Pengfei Ju,Guoliang Li,Xiaogang Li,Dawei Zhang
Antimicrobial resistance (AMR) from pathogenic bacterial biofilms has become a global health issue while developing novel antimicrobials is inefficient and costly. Combining existing multiple drugs with enhanced efficacy and/or reduced toxicity may be a promising approach to treat AMR. D-amino acids mixtures coupled with antibiotics can provide new therapies for drug-resistance infection with reduced toxicity by lower drug dosage requirements. However, iterative trial-and-error experiments are not tenable to prioritize credible drug formulations, owing to the extremely large number of possible combinations. Herein, a new avenue is provide to accelerate the exploration of desirable antimicrobial formulations via high-throughput screening and machine learning optimization. Such an intelligent method can navigate the large search space and rapidly identify the D-amino acid mixtures with the highest anti-biofilm efficiency and also the synergisms between D-amino acid mixtures and antibiotics. The optimized drug cocktails exhibit high antimicrobial efficacy while remaining non-toxic, which is demonstrated not only from in vitro assessments but also the first in vivo study using a lung infection mouse model.
研究领域:
药理学
·
微生物学
·
机器学习
·
生物技术
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产品关联
DOI
PubMed
高影响因子
BIOTECHNOLOGY AND BIOENGINEERING
·
2024
·
IF 3.5
Feng Cheng,Ke-Xiang Sun,Xiao-Xiao Gong,Wei Peng,Hua-Yue Zhang,Xi-Hang Liang,Ya-Ping Xue,Yu-Guo Zheng
D-amino acid oxidase (DAAO)-catalyzed selective oxidative deamination is a very promising process for synthesizing l -amino acids including l -phosphinothricin ( l -PPT, a high-efficiency and broad-spectrum herbicide). However, the wild-type DAAO's low activity toward unnatural substrates like d -phosphinothricin ( d -PPT) hampers its application. Herein, a DAAO from Caenorhabditis elegans ( Ce DAAO) was screened and engineered to improve the catalytic potential on d -PPT. First, we designed a novel growth selection system, taking into account the intricate relationship between the growth of Escherichia coli ( E. coli ) and the catalytic mechanism of DAAO. The developed system was used for high-throughput screening of gene libraries, resulting in the discovery of a variant (M6) with significantly increased catalytic activity against d -PPT. The variant displays different catalytic properties on substrates with varying hydrophobicity and hydrophilicity. Analysis using Alphafold2 modeling and molecular dynamic simulations showed that the reason for the enhanced activity was the substrate-binding pocket with enlarged size and suitable charge distribution. Further QM/MM calculations revealed that the crucial factor for enhancing activity lies in reducing the initial energy barrier of the reductive half reaction. Finally, a comprehensive binding-model index to predict the enhanced activity of DAAO toward d -PPT, and an enzymatic deracemization approach was developed, enabling the efficient synthesis of l -PPT with remarkable efficiency.
研究领域:
生物技术
·
酶学
·
蛋白质工程
·
计算生物学
·
化学生物学
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产品关联
DOI
PubMed
高影响因子
APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2018
·Vol. 102
·期 14
·6039-6046
·
IF 3.34
Tigu Fitsum,Zhang Junli,Liu Guoxia,Cai Zhen,Li Yin
d -Pantothenic acid (vitamin B 5 ) has wide applications in the feed, food, chemical, and pharmaceutical industries. Its biological production routes which employ pantothenate synthetase (PS) as the key enzyme are attractive since they avoid the tedious and time-consuming optical resolution process. However, little data is available on the activity and kinetics of this enzyme, hampering the rational selection of an efficient enzyme for the biological production of d -pantothenic acid. In this study, six phylogenetically distant PS-encoding genes, from Escherichia coli , Corynebacterium glutamicum , Bacillus subtilis , Bacillus thuringiensis , Bacillus cereus , and Enterobacter cloacae , were expressed in E. coli . The PS from C. glutamicum exhibited a specific activity of 205.1 U/mg and a turnover number of 127.6 s -1 , which to our best knowledge are the highest values ever reported. The addition of substrates ( d -pantoic acid and β-alanine) to the E. coli strain harboring this enzyme during the early log phase of fermentation resulted in the production of 97.1 g/L of d -pantothenic acid within 32 h, corresponding to a conversion yield of 99.1% and a productivity of 3.0 g/L/h. To the best of our knowledge, this is the highest productivity reported to date.
研究领域:
生物化学
·
微生物学
·
工业生物技术
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2016
·
IF 2.196
Dandan Han,Yumin Liu,Xiaona Li,Teng Zhang,Zhenfang Li,Shichao Du,Mingxia Guo,Shijie Xu,Bo Yu,Baohong Hou,Junbo Gong
The solubility of calcium d -pantothenate in (water + methanol) mixtures and the effect of β -alanine on the solubility of calcium d -pantothenate in a constant mole ratio of methanol and water was measured from 263.15 K to 303.15 K by the HPLC analysis method ( P = 0.1 MPa). The solubility of calcium d -pantothenate increased with increasing temperature in all the mixtures at constant composition. Besides, it also increased with mole fraction of water in (water + methanol) mixtures at a constant temperature. Additionally, the solubility of calcium d -pantothenate was enhanced by β -alanine at a given temperature. The experimental solubility in (water + methanol) mixtures was correlated by the modified Apelblat equation, the ternary NRTL equation and Solubility-Polarity Model. The Apelblat equation, the quaternary NRTL equation and the Cohn equation were adopted to correlate the experimental solubility in the (water + methanol + β -alanine) mixtures. Worthwhile, the quaternary NRTL equation was first applied to correlating the quaternary solid-liquid equilibrium. It turned out that all the selected models give good performance on solubility prediction.
研究领域:
药物化学
·
物理化学
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产品关联
DOI
高影响因子
JOURNAL OF CHROMATOGRAPHY A
·
2025
·
IF 4
Lei Ding,Chundan Ye,Junchen Zhu,Cuirong Sun
Chiral impurity analysis presents significant challenges due to limitations of detection methods. Levodopa (L-Dopa) is the primary medication for Parkinson's disease treatment for over 50 years. However, the detection of its chiral impurity is difficult due to the similarity of polarity. This study presents a novel analytical method for the quantitative detection of trace amount of D-Dopa, as well as other three impurities. The method demonstrated excellent chromatographic resolution for D-Dopa and L-Dopa (resolution = 4.15) and achieved a derivatization efficiency of 97% using a chlorine-labeled chiral probe (D-BPCl) for chemical derivatization, followed by analysis with liquid chromatography-tandem mass spectrometry (LC-MS/MS) on a conventional C18 column. Meanwhile, D-BPCl showed strong chiral selectivity on D-Dopa, and the ratio of mass spectrometric response for labeled D-Dopa to that of L-enantiomers was 2.78-fold under the same condition. The developed method demonstrates high sensitivity with detection limits of 7.88 μ g L -1 for D-Dopa, and 9.85 μ g L -1 for L-Dopa, with good linearity for every analyte (R 2 > 0.99), recoveries ranging from 94.1% to 106.8%, and high repeatability with relative standard deviation (RSD) values predominantly below 5%. Then the method was applied to analyze fifteen batches of levodopa tablets from five manufacturers. D-Dopa was successfully detected with the corresponding content ranging from 0.15% to 0.44%, which suggests that D-Dopa are more likely generated during the production process. The study underscores the significant safety concerns regarding Dopa-containing medications.
研究领域:
药物分析
·
药物质量控制
·
手性分离
·
药物代谢
·
分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）