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Properties and catalytic mechanism of -glutamyltranspeptidase from NX-2

WANG Qian, YAO Zhong, XUN Zhijing, XU Xiaoying, XU Hong, WEI Ping

《化学科学与工程前沿（英文）》 2008年第2卷第4期页码 456-461 doi: 10.1007/s11705-008-0075-3

摘要： Since -glutamyltranspeptidase (GGT) especially catalyses the transfer of the -glutamyl moiety to a variety of amino acids and short peptides, GGT has important practical value for enzymatic synthesis of -glutamyl compounds. In this paper, the GGT produced from NX-2 was purified by a combination of ammonium sulfate fractionation and ion exchange chromatography, and the properties of purified GGT were investigated. At the conditions of pH 10.0, D-glutamine (D-Gln)/L-tryptophan (L-Trp) with a molar ratio of 5 : 7, a temperature 40°C and a reaction time of 4 h, a higher conversion rate of 42% was obtained. According to the time course, the catalytic mechanism of enzymatic synthesis of -D-glutamyl-L-tryptophan (-D-Gln-L-Trp) was discussed. It was demonstrated that the GGT can catalyze not only the reaction of transpeptidation, but also the irreversible hydrolysis of the products which results in the decrease of the yield of the products. The affinity parameter of GGT to D-Gln (Km) was 5.08 mmol·L and the maximum reaction rate of transpeptidation () was determined as 0.034 mmol·min·L, while the affinity parameter of GGT to -D-Gln-L-Trp (’) was 2.267 mmol·L, and the maximum reaction rate of hydrolysis (’) was 0.012 mmol·min·L.

关键词： catalytic mechanism mmol·min·L D-glutamine affinity parameter important practical

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Recombinant aspartate aminotransferase-catalyzed synthesis of L-4-fluorophenylalanine

CHEN Meijuan, JIA Honghua, CHEN Yongsheng, JIANG Min, WEI Ping

《化学科学与工程前沿（英文）》 2008年第2卷第2期页码 220-223 doi: 10.1007/s11705-008-0041-0

摘要： L-4-Fluorophenylalanine (FPhe) was prepared from 4-fluorophenylpyruvate (FPPA) catalyzed by aspartate aminotransferase (Asp-AT) of the recombinant BL21-pET/aspC. After 12 h enzymatic reaction, the FPPA conversion was over 90% and the yield of FPhe could be above 85% under the following optimal conditions: 37°C, pH value range of 5.0–8.0, 5.5 mass ratio of cell to FPPA, 0.6% (w/v) of Tween 80, 7.08 g/L FPPA, and 1.6 of molar ratio of L-Asp to FPPA.

关键词： L-4-Fluorophenylalanine Asp-AT aspartate aminotransferase 4-fluorophenylpyruvate FPPA

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Influence of glucose feeding on the ligninolytic enzyme production of the white-rot fungus Phanerochaete chrysosporium

ZHOU Xiaoyan, WEN Xianghua, FENG Yan

《环境科学与工程前沿（英文）》 2007年第1卷第1期页码 89-94 doi: 10.1007/s11783-007-0017-1

摘要： The present work studied the influence of glucose feeding on the ligninolytic enzyme production of in a nitrogen-limited (C/N ratio is 56/8.8 mmol/L) medium. Several sets of shaking flask experiments were conducted. The results showed that 2 g/L glucose feeding on the first day of the culture (24 h after the inoculation) stimulated both fungal biomass growth and enzyme production. The manganese peroxidase (MnP) activity was 2.5 times greater than that produced in cultures without glucose feeding. Furthermore, the glucose feeding mode in fed-batch culture was also investigated. Compared to cultures with glucose feeding every 48 h, cultures with glucose feeding of 1.5 g/L (final concentration) every 24 h produced more enzymes. The peak and total yield of MnP activity were 2.7 and 3 times greater compared to the contrast culture, respectively, and the enzyme was kept stable for 4 days with an activity of over 200 U/L.

关键词： enzyme production fed-batch culture nitrogen-limited inoculation mmol/L

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Microbial communities biostimulated by ethanol during uranium (VI) bioremediation in contaminated sediment as shown by stable isotope probing

Mary Beth LEIGH,Wei-Min WU,Erick CARDENAS,Ondrej UHLIK,Sue CARROLL,Terry GENTRY,Terence L.

《环境科学与工程前沿（英文）》 2015年第9卷第3期页码 453-464 doi: 10.1007/s11783-014-0721-6

摘要： Stable isotope probing (SIP) was used to identify microbes stimulated by ethanol addition in microcosms containing two sediments collected from the bioremediation test zone at the US Department of Energy Oak Ridge site, TN, USA. One sample was highly bioreduced with ethanol while another was less reduced. Microcosms with the respective sediments were amended with C labeled ethanol and incubated for 7 days for SIP. Ethanol was rapidly converted to acetate within 24 h accompanied with the reduction of nitrate and sulfate. The accumulation of acetate persisted beyond the 7 d period. Aqueous U did not decline in the microcosm with the reduced sediment due to desorption of U but continuously declined in the less reduced sample. Microbial growth and concomitant C-DNA production was detected when ethanol was exhausted and abundant acetate had accumulated in both microcosms. This coincided with U(VI) reduction in the less reduced sample. C originating from ethanol was ultimately utilized for growth, either directly or indirectly, by the dominant microbial community members within 7 days of incubation. The microbial community was comprised predominantly of known denitrifiers, sulfate-reducing bacteria and iron (III) reducing bacteria including , , , and others, including the known U(VI)-reducing bacteria A , and The findings suggest that ethanol biostimulates the U(VI)-reducing microbial community by first serving as an electron donor for nitrate, sulfate, iron (III) and U(VI) reduction, and acetate which then functions as electron donor for U(VI) reduction and carbon source for microbial growth.

关键词： Stable isotope probing (SIP) ethanol acetate uranium reduction sediment bioremediation

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Comments on the special issue on forestry of

John L. INNES

《农业科学与工程前沿（英文）》 2017年第4卷第4期页码 502-503 doi: 10.15302/J-FASE-2017189

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PD-1/PD-L1 blockade in cervical cancer: current studies and perspectives

Yumeng Wang, Guiling Li

《医学前沿（英文）》 2019年第13卷第4期页码 438-450 doi: 10.1007/s11684-018-0674-4

摘要： Cervical cancer (CC) is the fourth most commonly diagnosed female malignancy and a leading cause of cancer-related mortality worldwide, especially in developing countries. Despite the use of advanced screening and preventive vaccines, more than half of all CC cases are diagnosed at advanced stages, when therapeutic options are extremely limited and side effects are severe. Given these circumstances, new and effective treatments are needed. In recent years, exciting progress has been made in immunotherapies, including the rapid development of immune checkpoint inhibitors. Checkpoint blockades targeting the PD-1/PD-L1 axis have achieved effective clinical responses with acceptable toxicity by suppressing tumor progression and improving survival in several tumor types. In this review, we summarize recent advances in our understanding of the PD-1/PD-L1 signaling pathway, including the expression patterns of PD-1/PD-L1 and potential PD-1/PD-L1-related therapeutic strategies for CC.

关键词： PD-1 PD-L1 immune checkpoint blockade antibody immunotherapy cervical cancer

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In memory of Perry L. McCarty, seminal founder of Environmental Biotechnology

《环境科学与工程前沿（英文）》 2023年第17卷第10期 doi: 10.1007/s11783-023-1730-0

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Shear design of high strength concrete prestressed girders

Emad L. LABIB,Hemant B. DHONDE,Thomas T. C. HSU,Y. L. MO

《结构与土木工程前沿（英文）》 2014年第8卷第4期页码 373-387 doi: 10.1007/s11709-014-0087-7

摘要： Normal strength prestressed concrete I-girders are commonly used as the primary superstructure components in highway bridges. However, shear design guidelines for high strength PC girders are not available in the current structural codes. Recently, ten 7.62 m (25 feet) long girders made with high strength concrete were designed, cast, and tested at the University of Houston (UH) to study the ultimate shear strength and the shear concrete contribution ( ) as a function of concrete strength ( ). A simple semi-empirical set of equations was developed based on the test results to predict the ultimate shear strength of prestressed concrete I-girders. The UH-developed set of equations is a function of concrete strength ( ), web area ( ), shear span to effective depth ratio ( / ), and percentage of transverse steel ( ). The proposed UH-Method was found to accurately predict the ultimate shear strength of PC girders with concrete strength up to 117 MPa (17000 psi) ensuring satisfactory ductility. The UH-Method was found to be not as overly conservative as the ACI-318 (2011) code provisions, and also not to overestimate the ultimate shear strength of high strength PC girders as the AASHTO LRFD (2010) code provisions. Moreover, the proposed UH-Method was found fairly accurate and not exceedingly conservative in predicting the concrete contribution to shear for concrete strength up to 117 MPa (17000 psi).

关键词： shear design high strength concrete prestressed girders full-scale tests

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Introduction to the special section on the 12

Zhen-Min CHENG

《化学科学与工程前沿（英文）》 2009年第3卷第1期页码 1-1 doi: 10.1007/s11705-009-0003-1

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Deeply missing my career idol and role model ― Professor Perry L. McCarty

《环境科学与工程前沿（英文）》 2023年第17卷第9期 doi: 10.1007/s11783-023-1717-x

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Distributed coordination inmulti-agent systems: a graph Laplacian perspective

Zhi-min HAN,Zhi-yun LIN,Min-yue FU,Zhi-yong CHEN

《信息与电子工程前沿（英文）》 2015年第16卷第6期页码 429-448 doi: 10.1631/FITEE.1500118

摘要： This paper reviews some main results and progress in distributed multi-agent coordination from a graph Laplacian perspective. Distributed multi-agent coordination has been a very active subject studied extensively by the systems and control community in last decades, including distributed consensus, formation control, sensor localization, distributed optimization, etc. The aim of this paper is to provide both a comprehensive survey of existing literature in distributed multi-agent coordination and a new perspective in terms of graph Laplacian to categorize the fundamental mechanisms for distributed coordination. For different types of graph Laplacians, we summarize their inherent coordination features and specific research issues. This paper also highlights several promising research directions along with some open problems that are deemed important for future study.

关键词： Multi-agent systems Distributed coordination Graph Laplacian

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Urban watershed management under rapid urbanization

Pengfei DU, Haifeng JIA, Shaw L. YU

《环境科学与工程前沿（英文）》 2012年第6卷第5期页码 595-595 doi: 10.1007/s11783-012-0452-5

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Effects of different doses of cadmium on secondary metabolites and gene expression in Artemisia annua L.

null

《医学前沿（英文）》 2017年第11卷第1期页码 137-146 doi: 10.1007/s11684-016-0486-3

摘要：

This study aims to elucidate the underlying molecular mechanisms of artemisinin accumulation induced by cadmium (Cd). The effects of different Cd concentrations (0, 20, 60, and 120 μmol/L) on the biosynthesis of Artemisia annua L. were examined. Intermediate and end products were quantified by HPLC-ESI-MS/MS analysis. The expression of key biosynthesis enzymes was also determined by qRT-PCR. The results showed that the application of treatment with 60 and 120 μmol/L Cd for 3 days significantly improved the biosynthesis of artemisinic acid, arteannuin B, and artemisinin. The concentrations of artemisinic acid, arteannuin B, and artemisinin in the 120 μmol/L Cd-treated group were 2.26, 102.08, and 33.63 times higher than those in the control group, respectively. The concentrations of arteannuin B and artemisinin in 60 μmol/L Cd-treated leaves were 61.10 and 26.40 times higher than those in the control group, respectively. The relative expression levels of HMGR, FPS, ADS, CYP71AV1, DBR2, ALDH1, and DXR were up-regulated in the 120 μmol/L Cd-treated group because of increased contents of artemisinic metabolites after 3 days of treatment. Hence, appropriate doses of Cd can increase the concentrations of artemisinic metabolites at a certain time point by up-regulating the relative expression levels of key enzyme genes involved in artemisinin biosynthesis.

关键词： Cd secondary metabolites gene expressions Artemisia annua L.

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Reactive extraction for preparation of hydrogen peroxide under pressure

CHENG Yongxi, LI Hongtao, WANG Li, LÜ Shuxiang

《化学科学与工程前沿（英文）》 2008年第2卷第3期页码 335-340 doi: 10.1007/s11705-008-0042-z

摘要： The preparation of hydrogen peroxide from anthrahydroquinone by reactive extraction was investigated. The integration process of oxidation of anthrahydroquinone by air and extraction of hydrogen peroxide from the organic phase with water was carried out in a sieve plate column under pressure. The conversion of anthrahydroquinone increased with increasing pressure resulting in an increase of hydrogen peroxide concentration in the aqueous phase. However, no change in extraction efficiency of hydrogen peroxide was observed. A mathematical model for gas-liquid-liquid reactive extraction was established. In the model, the effects of pressure and gas superficial velocity on reaction were considered. With increasing gas superficial velocity, the conversion of anthrahydroquinone increased, and the fraction of hydrogen peroxide extracted reached a plateau with a maximum of 72.94%. However, both the conversion of anthrahydroquinone and the fraction of hydrogen peroxide extracted decreased with increasing organic phase superficial velocity.

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地下工程的发展提升现代生活质量

Raymond L. Sterling

《工程（英文）》 2017年第3卷第6期页码 780-781 doi: 10.1016/j.eng.2017.12.006