检索结果-南通市图书馆

Study on Substrate Specificity at Subsites for Severe Acute Respiratory Syndrome Coronavirus 3CL Protease

在线全文

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2005年第12期37卷 807-813页

作者： Yu-Fei SHAN~1 Gen-Jun XU~(1,2)1 Institute of Bichemistry and Cell Biology.Shanghai Institutes for Biological sciences,Chinese Academy of sciences,Shanghai 200031,china 2 college of life science zhejiang sci-tech university,hangzhou 310018,china Institute of Biochemistry and Cell Biology Shanghai Institutes for Biological SciencesChinese Academy of SciencesShanghai 200031China college of life science Zhejiang Sci-Tech UniversityHangzhou 310018China

Autocleavage assay and peptide-based cleavage assay were used to study the substratespecificity of 3CL protease from the severe acute respiratory syndrome *** was found that therecognition between the enzyme and its substrates involved many positions in the substrate,at least includingresidues from P4 to P2′.The deletion of either P4 or P2′residue in the substrate would decrease its cleavageefficiency *** contrast to the previous suggestion that only small residues in substrate could beaccommodated to the S1′subsite,we have found that bulky residues such as Tyr and Trp were also *** addition,based on both peptide-based assay and autocleavage assay,Ile at the P1′position could not behydrolyzed,but the mutant L27A could hydrolyze the Ile peptide *** suggested that there was astereo hindrance between the S1′subsite and the side chain of Ile in the *** 20 amino acids exceptPro could be the residue at the P2′position in the substrate,but the cleavage efficiencies were *** specificity information of the enzyme is helpful for potent anti-virus inhibitor design and usefulfor other coronavirus studies.

关键词： SARS coronavirus 3CL protease substrate specificity autocleavage binding site inhibitor design

Purification and Characterization of Two Endo-β-1,4-glucanases from Mollusca,Ampullaria crossean

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2005年第10期37卷 702-708页

作者： Yan-Hong LI~(1#) Rui GUO~(3#) Qiu-Yu YIN~1 Ming DING~1 Si-Liang ZHANG~3 Gen-Jun XU~(1,2) Fu-Kun ZHAO~(1,2*) 1 Key Laboratory of Proteomics,Institute of Biochemistry and Cell Biology,Shanghai Institutes for Biological sciences.Graduate School of the Chinese Academy of sciences,Chinese Academy of sciences,Shanghai 200031,china 2 college of life science,zhejiang sci-tech university,hangzhou 310018,china 3 Bioengineering Institute,East china university of science and technology,Shanghai 200233,china KeyLaboratoryofProteomics InstituteofBiochemistryandCellBiologyShanghaiInstitutesforBiologicalSciencesGrad

Two novel endo-β-1,4-glucanases,EG45 and EG27,were isolated from the gastric juice ofmollusca,Ampullaria crossean,by anion exchange,hydrophobic interaction,gel filtration and a secondround of anion exchange *** purified proteins EG45 and EG27 appeared as a single bandon sodium dodecylsulfate polyacrylamide gel electrophoresis with a molecular mass of 45 kDa and 27 kDa,*** optimum pH for CMC activity was 5.5 for EG45 and 4.4-4.8 for *** optimumtemperature range for EG27 was broad,between 50℃ and 60℃;for EG45 it was 50℃.The analysis on thestability of these two endo-β-1,4-glucanases showed that EG27 was acceptably stable at pH 3.0-11.0 evenwhen the incubation time was prolonged to 24 h at 30℃,whereas EG45 remained relatively stable at *** 85% of the activity of EG27 could be retained upon incubation at 60℃ for 24 ***,less than 10% residual activity of EG45 was detected at 50℃.Among different kinds of substrates,bothenzymes showed a high preference for carboxymethyl ***45,in particular,showed a carboxymethylcellulose hydrolytic activity of 146.5 IU/mg *** enzymes showed low activities to xylan (from oatspelt) and Sigmacell 101,and they were inactive to p-nitrophenyl-β-D-cellobioside,salicin and starch.

关键词： cellulase endo-β-1,4-glucanase Ampullaria crossean purification substrate specificity

Expression and Identification of Mutated Osteoprotegerin in Culture Cells and Larvae of Silkworm

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2004年第5期36卷 331-335页

作者： Hai-Long XIAO, Yong-Feng JIN, and Yao-Zhou ZHANG1* Institute of Biochemistry, college of life sciences, zhejiang university, hangzhou 310029, china college of life sciences, zhejiang university of science & technology, hangzhou 310018, china college of life sciences Zhejiang University of Science & TechnologyHangzhou 310018China Institute of Biochemistry College of Life SciencesZhejiang UniversityHangzhou 310029China

The mutated osteoprotegerin (OPG-372) gene was inserted into the baculovirus transfer vector pBacPAK8, and the recombinant plasmid was co-transfected with linearized Bm-BacPAK6 virus DNA into BmN cells, then homologous recombination occurred inside the cells. The recombinant virus BmNPV-OPG- 372 was screened and identified by Southern blotting. The recombinant human OPG-372 was expressed in cultured cells and the larvae of silkworm by inoculation of recombinant virus. The expression products were run on the SDS-PAGE and their immunoreactivities were determined by Western blotting. It was found that a 42 kD recombinant protein was expressed in BmN cells and a 46 kD one in larvae respectively. The bioactivi- ties of the recombinant proteins were determined by hypocalcemic effect assay in the mice. The results showed that the recombinant proteins had a significant hypocalcemic effect on mice sera.

关键词： OPG-372 silkworm baculovirus expression system hypocalcemic effect

Noether-type theory for discrete mechanico-electrical dynamical systems with nonregular lattices

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1687-1698页

作者： FU JingLi1,CHEN LiQun2 & CHEN BenYong3 1 Institute of Mathematical Physics,zhejiang sci-tech university,hangzhou 310018,china 2 Department of Mechanics,Shanghai university,Shanghai 200072,china 3 Faculty of Mechanical-Engineering & Automation,zhejiang sci-tech university,hangzhou 310018,china 1. Institute of Mathematical Physics Zhejiang Sci-Tech University Hangzhou 310018 China2. Department of Mechanics Shanghai University Shanghai 200072 China3. Faculty of Mechanical-Engineering & Automation Zhejiang Sci-Tech University Hangzhou 310018 China

We investigate Noether symmetries and conservation laws of the discrete mechanico-electrical systems with nonregular *** operators of discrete transformation and discrete differentiation to the right and left are introduced for the *** on the invariance of discrete Hamilton action on nonregular lattices of the systems with the dissipation forces under the infinitesimal transformations with respect to the time,generalized coordinates and generalized charge quantities,we work out the discrete analog of the generalized variational *** this formula we derive the discrete analog of generalized Noether-type identity,and then we present the generalized quasi-extremal equations and properties of these equations for the *** also obtain the discrete analog of Noether-type conserved laws and the discrete analog of generalized Noether theorems for the *** we use an example to illustrate these results.

关键词： Noether symmetry variational formula quasi-extremal equation conservation law discrete mechanico-electrical dynamical system

Impact Factors of Energy Productivity in china: An Empirical Analysis

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Population,Resources and Environment 2007年第2期5卷 28-33页

作者： Wei Chu1,2, Shen Manhong2 1. college of Economics and Management, zhejiang sci-tech university, hangzhou zhejiang 310018, china 2. college of Economics, zhejiang university, hangzhou zhejiang 310017, china college of Economics and Management Zhejiang Sci-Tech University Zhejiang 310018 Hangzhou China college of Economics Zhejiang University Zhejiang 310017 Hangzhou China

This article developed a decomposition model of energy productivity on the basis of the economic growth model. Four factors were considered which may influence china’s energy productivity according to this model: technology improvement, resource allocation structure, industrial structure and institute arrangement. Then, an econometric model was employed to test the four factors empirically on the basis of china’s statistical data from 1978 to 2004. Results indicated that capital deepening con- tributes the most (207%) to energy efficiency improvement, and impact from labor forces (13%) is the weakest one in resource factor; industrial structure (7%) and institute innovation (9.5%) positively improve the energy productivity.

关键词： energy productivity impact factor economic growth china

Group sparse representation for image categorization and semantic video retrieval

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2011年第10期54卷 2051-2063页

作者： LIU YaNan 1,2 ,WU Fei 2 & ZHUANG YueTing 2 1 School of Information,zhejiang university of Finance & Economics,hangzhou,310018,china 2 college of Computer science and technology,zhejiang university,hangzhou,310012,china 1. School of Information Zhejiang University of Finance & Economics Hangzhou 310018 China2. College of Computer Science and Technology Zhejiang University Hangzhou 310012 China

Multimedia content analysis and management are a promising and challenging *** this paper we develop a novel approach to image representation,which we call group sparse representation (GSR),for image classification and video *** basic idea is to represent a test image as a weighted combination of all the training *** particular,we introduce two sets of weight coefficients,one for each training image and the other for each ***,we formulate our concern as a group nonnegative garrote *** resulting representations are sparse,and they are appropriate for discriminant *** on Caltech101 and PASCAL VOC2008 image dataset and TRECVID2005 video corpus testify that our proposed approach is efficient and effective.

关键词： compressive sensing group sparse representation bag-of-SIFT-words nonnegative garrote l1-minimization apcluster

pH-Dependent Stability of EGX, A Multi-functional Cellulase from Mollusca, Ampullaria crossean

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2004年第9期36卷 603-608页

作者： Wen-Ying LI2, Ji WANG1, Yan-Hong LI1, Ming DING1, Gen-Jun XU1,3, Lan-Ying LIU2, and Fu-Kun ZHAO1,3* 1Key Laboratory of Proteomics, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological sciences, the Chinese Academy of sciences,Graduate School of the Chinese Academy of sciences, Shanghai 200031, china 2college of life science, Jilin university, Changchun 130023, china college of life science, zhejiang university of science and technology, hangzhou 310018, china Key Laboratory ofProteomics Institute of Biochemistry and Cell BiologyShanghai Institutes for Biological Sciencesthe Chinese Academy of SciencesGraduate School of the Chinese Academy of SciencesShanghai 200031China

The cellulase activity and stability of EGX, a multi-functional cellulase previously purified from the mollusca Ampullaria crossean, was systematically studied under different pH. The pH induced con- formation and stability change of EGX have been investigated by using the intrinsic fluorescence, ANS fluorescence and CD spectrum. It has been found that the conformation and activity of this cellulase were strongly dependent on the pH. EGX was stable for both the enzyme activity and the conformation from pH 5.6 to pH 7.4. As shown by intrinsic and ANS fluorescence, no red shift of emission maximum occurred and a negligible intensity change was observed at pH 5.6–7.4. The activity of EGX remained about 80% in pH 5.6–7.4 and obviously decreased out of side the pH range. Urea-induced changes in EGX at pH 5.4 and pH 8.0 were measured by intrinsic fluorescence and CD spectrum. At pH 5.4, a significantly red shift of emission maximum occurred when the concentration of urea was 5 M compared to the concentration was 3 M at pH 8.0. The α-helix at pH 5.4 was 40.51% in the absence of urea and 31.04% in the presence of 4 M urea. At pH 8.0 the α-helix was 7.23% in the presence of 4 M urea. The data indicated that EGX was much susceptible to urea-induced unfolding at pH 8.0 and much stable at pH 5.4. The greater pH dependent stability of EGX may allow the enzyme to adequately catalyze the hydrolysis of cellulosic materials under natural or industrial extreme conditions.

关键词： multi-functional cellulase stability Ampullaria crossean fluorescence spectroscopy pH-dependent structural change CD spectrum

Purification and characterization of keratinase from a new Bacillus subtilis strain

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of zhejiang university-science B(Biomedicine & Biotechnology) 2008年第9期9卷 713-720页

作者： Cheng-gang CAI1,2, Ji-shuang CHEN3, Jiong-jiong QI2, Yun YIN2, Xiao-dong ZHENG2 (1college of Biology and Environmental Engineering, zhejiang Shuren university, hangzhou 310015, china) (2college of Food science and Biosystem Engineering, zhejiang university, hangzhou 310029, china) (3Institute of Bioengineering, zhejiang sci-tech university, Hongzhou 310018, china) college of Biology and Environmental Engineering Zhejiang Shuren University Hangzhou 310015 China college of Food science and Biosystem Engineering Zhejiang University Hangzhou 310029 China.

The aim of this study was to purify and characterize a keratinase produced by a new isolated Bacillus subtilis KD-N2 strain. The keratinase produced by the isolate was purified using ammonium sulphate precipitation, Sephadex G-75 and DEAE (diethylaminoethyl)-Sepharose chromatographic techniques. The purified enzyme was shown to have a molecular mass of 30.5 kDa, as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The optimum pH at 50 °C was 8.5 and the optimum temperature at pH 8.5 was 55 °C. The keratinase was partially inactivated by some metal ions, organic solvents and serine protease inhibitor phenylmethanesulfonyl fluoride (PMSF). Sodium dodecyl sulfate (SDS) and ethylene diamine tetraacetic acid (EDTA) had positive effect on the keratinase activity. Reducing agents including dithiothreitol (DTT), mercaptoethanol, L-cysteine, sodium sulphite, as well as chemicals of SDS, ammonium sulfamate and dimethylsulfoxide (DMSO) stimulated the enzyme activity upon a feather meal substrate. Besides feather keratin, the enzyme is active upon the soluble proteins ovalbumin, bovine serum albumin (BSA), casein and insoluble ones as sheep wool and human hair. Calf hair, silk and collagen could not be hydrolyzed by the keratinase.

关键词： Ammonium sulfatate Bacillus subtilis Characterization Feather Keratin Keratinase Purification Reducing agents

Symmetries and exact solutions of discrete nonconservative systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1699-1706页

作者： FU JingLi1,LI XiaoWei2,LI ChaoRong1,ZHAO WeiJia3 & CHEN BenYong4 1 Institute of Mathematical Physics,zhejiang sci-tech university,hangzhou 310018,china 2 Department of Physics,Shangqiu Normal university,Shangqiu 476000,china 3 Department of Mathematics,Qingdao university,Qingdao 266071,china 4 Faculty of Mechanical Engineering & Automation,zhejiang sci-tech university,hangzhou 310018,china 1. Institute of Mathematical Physics Zhejiang Sci-Tech University Hangzhou 310018 China2. Department of Physics Shangqiu Normal University Shangqiu 476000 China3. Department of Mathematics Qingdao University Qingdao 266071 China4. Faculty of Mechanical Engineering & Automation Zhejiang Sci-Tech University Hangzhou 310018 China

Based on the property of the discrete model entirely inheriting the symmetry of the continuous system,we present a method to construct exact solutions with continuous groups of transformations in discrete nonconservative *** Noether's identity of the discrete nonconservative system is *** symmetric discrete Lagrangian and symmetric discrete nonconservative forces are defined for the *** quasi-extremal equations of discrete nonconservative systems are *** conserved quantities are derived with symmetries associated with the continuous *** have also found that the existence of the one-parameter symmetry group provides a reduction to a conserved quantity;but the existence of a two-parameter symmetry group makes it possible to obtain an exact solution for a discrete nonconservative *** examples are discussed to illustrate these results.

关键词： discrete nonconservative system symmetry conserved quantity quasi-extremal equation exact solution