Enhancing catalytic activity of multi-enzyme in vitro through substrate channeling effect is promis-ing yet challenging.Herein,conjugated microporous polymers(CMPs)-scaffolded integrated en-zyme cascade systems(I-ECSs...Enhancing catalytic activity of multi-enzyme in vitro through substrate channeling effect is promis-ing yet challenging.Herein,conjugated microporous polymers(CMPs)-scaffolded integrated en-zyme cascade systems(I-ECSs)are constructed through co-entrapping glucose oxidase(GOx)and horseradish peroxidase(HRP),in which hydrogen peroxide(H_(2)O_(2)) is the intermediate product.The interplay of low-resistance mass transfer pathway and appropriate pore wall-H_(2)O_(2) interactions facilitates the directed transfer of H_(2)O_(2),resulting in 2.4-fold and 5.0-fold elevation in catalytic activ-ity compared to free ECSs and separated ECSs,respectively.The substrate channeling effect could be regulated by altering the mass ratio of GOx to HRP.Besides,I-ECSs demonstrate excellent stabili-ties in harsh environments and multiple recycling.展开更多
Plant RNA N-glycosidase specifically hydrolyzes the N-C glycosidic bond of a conserved adenosine in the sarcin/ricin domain of the largest RNA in ribosome, releasing an adenine base and thus inhibiting protein synthes...Plant RNA N-glycosidase specifically hydrolyzes the N-C glycosidic bond of a conserved adenosine in the sarcin/ricin domain of the largest RNA in ribosome, releasing an adenine base and thus inhibiting protein synthesis. This substrate specificity was challenged later by discovery that various RNA derivatives and DNAs, especially the double-stranded supercoiled DNA could be used as substrate by RNA N-glycosidase. Thus, it was argued whether the DNA-cleaving activity was an intrinsic feature of RNA N-glycosidase or it was contaminated by DNase. In this article, several lines of evidence are presented to show that RNA N-glycosidase can really release the adenine base from the double-stranded supercoi/ed DNA. It was proposed that the cleavage mechanism of supercoiled DNA was the phosphodiester bonds in enzymatically deadenylated regions of the supercoiled DNA would become fragile and liable to produce nicked or linear form owing to the existence of tension in the supercoiled DNA molecule, not direct result of enzymatic action on the phosphodiester bond.展开更多
The purpose of this research was to study learning retention in undergraduate biology students on the topic of enzyme properties by using simple enzyme activity from vegetables and fruits. A hands-on practical was dev...The purpose of this research was to study learning retention in undergraduate biology students on the topic of enzyme properties by using simple enzyme activity from vegetables and fruits. A hands-on practical was developed to simplify detection of enzyme activity of amylase, protease and lipase on starch agar, dry whole milk agar, and trihutyrin agar, respectively. The subjects of the study were 24 senior undergraduates who studied in the Program of General Science, Faculty of Science, Srinakharinwirot University, Bangkok, in three semesters during 2007 - 2008. The basic concepts of enzymes, e.g., substrate specificity, how to detect enzymes and optimal enzyme conditions, were taught before the practical. The first enzyme, protease, was used in the second semester of 2007, and then changed to be lipase and protease in the first and second semesters of 2008, respectively. Ten open-ended questions were used to assess students in all semesters. In agreement with the constructivist learning model, it was demonstrated that students had learning retention and applied their prior knowledge to other enzyme experiments.展开更多
Laccases are blue copper oxidases （E.C. 1.10.3.2 benzenediol：oxygen oxidoreductase） that catalyze the one-electron oxidation of phenolics, aromatic amines and other electron-rich substrates with the concomitant red...Laccases are blue copper oxidases （E.C. 1.10.3.2 benzenediol：oxygen oxidoreductase） that catalyze the one-electron oxidation of phenolics, aromatic amines and other electron-rich substrates with the concomitant reduction of 02 to H20. They are currently seen as highly interesting industrial enzymes because of their broad substrate specificity. The Phanerochaete flavido-alba laccase is expressed and secreted as a soluble active enzyme by Aspergillus niger （rLac-LPFA）. rLac-LPFA is easily purified to homogeneity. Metal ions like HgCI2, KC12, FeSO4 and MgSO4 at a concentration of 2 mM have inhibiting effect on recombinant and native laccase, whereas, CuSO4 and MnSO4 moderately increase both enzyme activities. Two potential inhibitors （sodium azide and EDTA） inhibited enzyme activity, whereas, urea and SDS have no effect on enzyme activity. The Km and V,,ax values for recombinant laccase are 0.65 mM and 300 U/mg respectively for 2,6-DMP as substrate.展开更多
A total of 28 yeast strains were obtained from the sea sediment of Antarctica.According to the results of routine identi-fication and molecular characterization,the strains belonged to species of Yarrowia lipolytica,D...A total of 28 yeast strains were obtained from the sea sediment of Antarctica.According to the results of routine identi-fication and molecular characterization,the strains belonged to species of Yarrowia lipolytica,Debaryomyces hansenii,Rhodotorula slooffiae,Rhodotorula mucilaginosa,Sporidiobolus salmonicolor,Aureobasidium pullulans,Mrakia frigida and Guehomyces pullu-lans,respectively.The Antarctica yeasts have wide potential applications in biotechnology,for some of them can produce b-galactosidase and killer toxins.展开更多
The present study was conducted for the optimization of pretreatment and enzymatic hydrolysis of lignocellulosic biomass （sugarcane trash）, which is a renewable resource for the production of bioethanol. The pretrea...The present study was conducted for the optimization of pretreatment and enzymatic hydrolysis of lignocellulosic biomass （sugarcane trash）, which is a renewable resource for the production of bioethanol. The pretreatment and enzymatic hydrolysis conditions including alkali （NaOH）/dilute acid （H2SO4）, substrate and chemical concentration for pretreatment, enzyme dosage, pH, temperature and substrate concentration for hydrolysis were varied and evaluated for sugar and ethanol production at the end. The optimum condition was accomplished using 15% w/v DS of 0-2 mm sugarcane trash in size of particle. It was pretreated with two steps of 2% w/v NaOH autoclaving followed by 2% w/v H2SO4 autoclaving with washing step after pretreatment. An enzymatic hydrolysis was then performed using 15% w/v DS pretreated substrate, hydrolyzed with cellulase 50 filter paper unit （FPU）/g DS at 50 ℃ and pH 5. After incubating at 160 r for 48 h, 117.16 g/L reducing sugar was obtained. The achieved sugar after enzymatic hydrolysis was finally fermented to ethanol by Saccharomyces cerevisiae TISTR 5596, with concentration of 48.17 g/L ethanol or yield 0.509 g/g reducing sugars which was equal to 99.81% of theoretical yield.展开更多
The Inohana Lake is a branch lake of the Hamana Lake. The Inohana Lake is an estuary rather than a brackish lake, and has suffered environmental problems such as eutrophication and bottom hypoxic water. In this study,...The Inohana Lake is a branch lake of the Hamana Lake. The Inohana Lake is an estuary rather than a brackish lake, and has suffered environmental problems such as eutrophication and bottom hypoxic water. In this study, the coupled hydrodynamic and ecological models （eco-hydrodynamic model） were used to construct the strategy for preventing the bottom hypoxic water and improving or recovering the water quality in the lake. Using the model input obtained from the summertime data over 1998-2002, the summer-average flow field and oxygen concentration and budget of the standard run were calculated. Remedial measures used in this study are divided into two parts： the biogeochemical and physical changes in the present situation. For the remedial measures including the biogeochemical changes in the present situation, the simulations considering the reductions of the nutrient inputs from the river, main lake （land） and bottom sediment, and the sediment oxygen demand （SOD） were carried out. For the remedial measures including the physical changes, the 50 and 100 m extensions of the inlet width were considered in the model runs. These simulated results were compared in terms of changes in the dissolved oxygen （DO） concentration and oxygen budget in the bottom layer in the Inohana Lake. There was no significant change in the DO concentration and oxygen stock in the simulations for the reduction of the nutrient inputs from the land and bottom sediment, however increases in those in the simulations for the reduction of SOD. When SOD was reduced by 50%, the bottom DO concentration increased by approximately 2 mg/L and the oxygen stock in the bottom layer increased by 47% comparing the present situation （the standard run） of the lake. The simulation results for inlet width extension showed that the extension of width makes the DO concentration and oxygen stock lower. The remedial measures for the sediment control were proposed to prevent the bottom hypoxia and manage the water quality.展开更多
To explore the effect of puerarin on insulin receptor （IR）, insulin receptor substrate-1 （IRS-1） and protein expression of protein kinase B （PKB） in the P13K pathway of the glucose consumption, transportation an...To explore the effect of puerarin on insulin receptor （IR）, insulin receptor substrate-1 （IRS-1） and protein expression of protein kinase B （PKB） in the P13K pathway of the glucose consumption, transportation and insulin signal transduction in 3T3-L1 adipoeytes with insulin resistance. The insulin resistance 3T3-L1 adipocytes model was established by free fatty acid induction. The model cells were managed with puerarin in different concentrations. Glucose consumption was detected with glucose oxidase method, glucose transportation rate was determined by 2-deoxy-^3H glucose ingesting method, and the IR, IRS-1 and PKB expression were determined by Western blot. Glucose consumption and transportation were significantly decreased in the model adipoeytes, but increased after treated with puerarin （P 〈 0. 01 ）. Moreover, the level of tyrosine phosphorylation of IR subunit β was higher in the puerarin treated groups, and that of IRS-1 was higher in the group treated with low dose puerarin than that in the model group. The 3T3-L1 adipocytes of insulin resistance model could be induced by free fatty acid successfully, puerarin could promote the glucose utilization in them to alleviate the in- sulin resistance, which may be related with the action in advancing the tyrosine phosphorylation of IR and IRS-1.展开更多
It is believed that amyloid-βpeptide（Aβ）plays a central role in the pathogenesis of Alzheimer’s disease（AD）.Thus,the process of amyloid precursor protein（APP）cleavage is a key event and has raised much attent...It is believed that amyloid-βpeptide（Aβ）plays a central role in the pathogenesis of Alzheimer’s disease（AD）.Thus,the process of amyloid precursor protein（APP）cleavage is a key event and has raised much attention in the field of AD research.It is proposed that APP,β-andγ-secretases are all located on the lipid raft,and the meeting of them is an indispensable step for Aβgeneration.Endocytosis can lead to clustering of APP,β-andγ-secretases from separate smaller lipid rafts into a larger one.On the other hand,for myristoylated alanine-rich C kinase substrate（MARCKS）,phosphorylation by protein kinase C（PKC）or interaction with Ca2＋can lead to its release from membrane into cytoplasm.This process induces the release of actins and phosphatidylinositol 4,5-bisphosphate（PIP2）,which are important factors for endocytosis.Thus,the present review proposes that MARCKS may be implicated in Aβgeneration,by modulating free PIP 2 level and actin movement,causing endocytosis.展开更多
文摘Enhancing catalytic activity of multi-enzyme in vitro through substrate channeling effect is promis-ing yet challenging.Herein,conjugated microporous polymers(CMPs)-scaffolded integrated en-zyme cascade systems(I-ECSs)are constructed through co-entrapping glucose oxidase(GOx)and horseradish peroxidase(HRP),in which hydrogen peroxide(H_(2)O_(2)) is the intermediate product.The interplay of low-resistance mass transfer pathway and appropriate pore wall-H_(2)O_(2) interactions facilitates the directed transfer of H_(2)O_(2),resulting in 2.4-fold and 5.0-fold elevation in catalytic activ-ity compared to free ECSs and separated ECSs,respectively.The substrate channeling effect could be regulated by altering the mass ratio of GOx to HRP.Besides,I-ECSs demonstrate excellent stabili-ties in harsh environments and multiple recycling.
文摘Plant RNA N-glycosidase specifically hydrolyzes the N-C glycosidic bond of a conserved adenosine in the sarcin/ricin domain of the largest RNA in ribosome, releasing an adenine base and thus inhibiting protein synthesis. This substrate specificity was challenged later by discovery that various RNA derivatives and DNAs, especially the double-stranded supercoiled DNA could be used as substrate by RNA N-glycosidase. Thus, it was argued whether the DNA-cleaving activity was an intrinsic feature of RNA N-glycosidase or it was contaminated by DNase. In this article, several lines of evidence are presented to show that RNA N-glycosidase can really release the adenine base from the double-stranded supercoi/ed DNA. It was proposed that the cleavage mechanism of supercoiled DNA was the phosphodiester bonds in enzymatically deadenylated regions of the supercoiled DNA would become fragile and liable to produce nicked or linear form owing to the existence of tension in the supercoiled DNA molecule, not direct result of enzymatic action on the phosphodiester bond.
文摘The purpose of this research was to study learning retention in undergraduate biology students on the topic of enzyme properties by using simple enzyme activity from vegetables and fruits. A hands-on practical was developed to simplify detection of enzyme activity of amylase, protease and lipase on starch agar, dry whole milk agar, and trihutyrin agar, respectively. The subjects of the study were 24 senior undergraduates who studied in the Program of General Science, Faculty of Science, Srinakharinwirot University, Bangkok, in three semesters during 2007 - 2008. The basic concepts of enzymes, e.g., substrate specificity, how to detect enzymes and optimal enzyme conditions, were taught before the practical. The first enzyme, protease, was used in the second semester of 2007, and then changed to be lipase and protease in the first and second semesters of 2008, respectively. Ten open-ended questions were used to assess students in all semesters. In agreement with the constructivist learning model, it was demonstrated that students had learning retention and applied their prior knowledge to other enzyme experiments.
文摘Laccases are blue copper oxidases （E.C. 1.10.3.2 benzenediol：oxygen oxidoreductase） that catalyze the one-electron oxidation of phenolics, aromatic amines and other electron-rich substrates with the concomitant reduction of 02 to H20. They are currently seen as highly interesting industrial enzymes because of their broad substrate specificity. The Phanerochaete flavido-alba laccase is expressed and secreted as a soluble active enzyme by Aspergillus niger （rLac-LPFA）. rLac-LPFA is easily purified to homogeneity. Metal ions like HgCI2, KC12, FeSO4 and MgSO4 at a concentration of 2 mM have inhibiting effect on recombinant and native laccase, whereas, CuSO4 and MnSO4 moderately increase both enzyme activities. Two potential inhibitors （sodium azide and EDTA） inhibited enzyme activity, whereas, urea and SDS have no effect on enzyme activity. The Km and V,,ax values for recombinant laccase are 0.65 mM and 300 U/mg respectively for 2,6-DMP as substrate.
基金supported by the Hi-Tech Researchand Development Program of China(863),the grant No. is 2006AA09Z403
文摘A total of 28 yeast strains were obtained from the sea sediment of Antarctica.According to the results of routine identi-fication and molecular characterization,the strains belonged to species of Yarrowia lipolytica,Debaryomyces hansenii,Rhodotorula slooffiae,Rhodotorula mucilaginosa,Sporidiobolus salmonicolor,Aureobasidium pullulans,Mrakia frigida and Guehomyces pullu-lans,respectively.The Antarctica yeasts have wide potential applications in biotechnology,for some of them can produce b-galactosidase and killer toxins.
文摘The present study was conducted for the optimization of pretreatment and enzymatic hydrolysis of lignocellulosic biomass （sugarcane trash）, which is a renewable resource for the production of bioethanol. The pretreatment and enzymatic hydrolysis conditions including alkali （NaOH）/dilute acid （H2SO4）, substrate and chemical concentration for pretreatment, enzyme dosage, pH, temperature and substrate concentration for hydrolysis were varied and evaluated for sugar and ethanol production at the end. The optimum condition was accomplished using 15% w/v DS of 0-2 mm sugarcane trash in size of particle. It was pretreated with two steps of 2% w/v NaOH autoclaving followed by 2% w/v H2SO4 autoclaving with washing step after pretreatment. An enzymatic hydrolysis was then performed using 15% w/v DS pretreated substrate, hydrolyzed with cellulase 50 filter paper unit （FPU）/g DS at 50 ℃ and pH 5. After incubating at 160 r for 48 h, 117.16 g/L reducing sugar was obtained. The achieved sugar after enzymatic hydrolysis was finally fermented to ethanol by Saccharomyces cerevisiae TISTR 5596, with concentration of 48.17 g/L ethanol or yield 0.509 g/g reducing sugars which was equal to 99.81% of theoretical yield.
文摘The Inohana Lake is a branch lake of the Hamana Lake. The Inohana Lake is an estuary rather than a brackish lake, and has suffered environmental problems such as eutrophication and bottom hypoxic water. In this study, the coupled hydrodynamic and ecological models （eco-hydrodynamic model） were used to construct the strategy for preventing the bottom hypoxic water and improving or recovering the water quality in the lake. Using the model input obtained from the summertime data over 1998-2002, the summer-average flow field and oxygen concentration and budget of the standard run were calculated. Remedial measures used in this study are divided into two parts： the biogeochemical and physical changes in the present situation. For the remedial measures including the biogeochemical changes in the present situation, the simulations considering the reductions of the nutrient inputs from the river, main lake （land） and bottom sediment, and the sediment oxygen demand （SOD） were carried out. For the remedial measures including the physical changes, the 50 and 100 m extensions of the inlet width were considered in the model runs. These simulated results were compared in terms of changes in the dissolved oxygen （DO） concentration and oxygen budget in the bottom layer in the Inohana Lake. There was no significant change in the DO concentration and oxygen stock in the simulations for the reduction of the nutrient inputs from the land and bottom sediment, however increases in those in the simulations for the reduction of SOD. When SOD was reduced by 50%, the bottom DO concentration increased by approximately 2 mg/L and the oxygen stock in the bottom layer increased by 47% comparing the present situation （the standard run） of the lake. The simulation results for inlet width extension showed that the extension of width makes the DO concentration and oxygen stock lower. The remedial measures for the sediment control were proposed to prevent the bottom hypoxia and manage the water quality.
基金Sponsored by the Postdoctoral Fund of Heilongjiang Province
文摘To explore the effect of puerarin on insulin receptor （IR）, insulin receptor substrate-1 （IRS-1） and protein expression of protein kinase B （PKB） in the P13K pathway of the glucose consumption, transportation and insulin signal transduction in 3T3-L1 adipoeytes with insulin resistance. The insulin resistance 3T3-L1 adipocytes model was established by free fatty acid induction. The model cells were managed with puerarin in different concentrations. Glucose consumption was detected with glucose oxidase method, glucose transportation rate was determined by 2-deoxy-^3H glucose ingesting method, and the IR, IRS-1 and PKB expression were determined by Western blot. Glucose consumption and transportation were significantly decreased in the model adipoeytes, but increased after treated with puerarin （P 〈 0. 01 ）. Moreover, the level of tyrosine phosphorylation of IR subunit β was higher in the puerarin treated groups, and that of IRS-1 was higher in the group treated with low dose puerarin than that in the model group. The 3T3-L1 adipocytes of insulin resistance model could be induced by free fatty acid successfully, puerarin could promote the glucose utilization in them to alleviate the in- sulin resistance, which may be related with the action in advancing the tyrosine phosphorylation of IR and IRS-1.
基金supported by the National Natural Science Foundation of China(No.30701137)
文摘It is believed that amyloid-βpeptide（Aβ）plays a central role in the pathogenesis of Alzheimer’s disease（AD）.Thus,the process of amyloid precursor protein（APP）cleavage is a key event and has raised much attention in the field of AD research.It is proposed that APP,β-andγ-secretases are all located on the lipid raft,and the meeting of them is an indispensable step for Aβgeneration.Endocytosis can lead to clustering of APP,β-andγ-secretases from separate smaller lipid rafts into a larger one.On the other hand,for myristoylated alanine-rich C kinase substrate（MARCKS）,phosphorylation by protein kinase C（PKC）or interaction with Ca2＋can lead to its release from membrane into cytoplasm.This process induces the release of actins and phosphatidylinositol 4,5-bisphosphate（PIP2）,which are important factors for endocytosis.Thus,the present review proposes that MARCKS may be implicated in Aβgeneration,by modulating free PIP 2 level and actin movement,causing endocytosis.
