Thermophilic esterase APE1547 from Aeropyrum pernix K1 contained a β-propeller with seven blades. There are three hydrogen bonding interactions(Thr127-Gly154,Leu182- Arg145-Glu122) between blades 3 and 4 in the β-pr...Thermophilic esterase APE1547 from Aeropyrum pernix K1 contained a β-propeller with seven blades. There are three hydrogen bonding interactions(Thr127-Gly154,Leu182- Arg145-Glu122) between blades 3 and 4 in the β-propeller domain of the APE1547. To examine the role of these hydrogen bonds, we eliminated these three hydrogen bonds between blades 3 and 4, by site-directed mutagenesis. The analysis results of kinetics, thermostability and differential scanning calorimetry(DSC) of the mutants show that Kcat/Km value of each mutation increased, and stability decreased dramatically than wild-type protein. These results strongly suggest that the three specific hydrogen bonds played an important role on maintaining the stability and activity of the esterase APE1547.展开更多
Hyperthermophilic enzyme APE1547 is an extremely thermostable recombinant protein from thermophilic archaeon Aeropyrumpernix K1. The Tyr444 located in the catalytic domain adjacent to the catalytic amino acid Ser445 a...Hyperthermophilic enzyme APE1547 is an extremely thermostable recombinant protein from thermophilic archaeon Aeropyrumpernix K1. The Tyr444 located in the catalytic domain adjacent to the catalytic amino acid Ser445 and formed hydrogen bond with Ile567. To study the effect of Tyr444 on the activity of APE1547, site-directed mutagenesis was applied. Two mutant enzymes T444S and T444G were created. Comparison of the mutant enzymes with wide enzyme, the thermostability of mutants T444S and T444G decreased by 10%-20%, but the catalytic efficiency of mutants toward pNPC8 and Ac-Leu-pNA increased 1.33 and 1.75 fold respectively. Molecular modeling shows that the elimination of hydrogen bond between Tyr444 and Ile567 is the cause of the decrease in thermostability and increase in catalytic efficiency. These observations suggest that Tyr444 plays an important role in the catalytic ability and thermostability of this enzyme.展开更多
Power conditioner, that is responsible for electric power conversion, is a critical component used in many renewable energy power generation systems. Most of the electric power produced by distributed energy resources...Power conditioner, that is responsible for electric power conversion, is a critical component used in many renewable energy power generation systems. Most of the electric power produced by distributed energy resources cannot directly import to utility network without power conversion. Meanwhile, power conversion may includes several different types, for example AC/DC, and DC/AC, which is realized by a variety types of power conditioners in the electric power system. Currently, many concerns are focused on the operation of these power conditioners used in distributed energy resources due to the worse designing may cause the terrible influence on safety and performance characteristic of distributed energy resources. The power quality and reliability of interconnected electric power network may be affected as well. In the view of this, IEEE standards board provides a uniform standard for interconnection of distributed resources with electric power systems. It provides requirements relevant to the performance, operation, testing, safety considerations, and maintenance of the interconnection. Based on the IEEE 1547 standard, this paper presents a test system for power conditioners that are used in distributed energy resources or other renewable energy applications. Some of the test items that described in IEEE 1547.1 relevant to interconnection issues can be realized by proposed test system.展开更多
In the present scenario,many solar photovoltaic(SPV)systems have been installed in the distribution network,most of them are operating at the unity power factor,which does not provide any reactive power support.In fut...In the present scenario,many solar photovoltaic(SPV)systems have been installed in the distribution network,most of them are operating at the unity power factor,which does not provide any reactive power support.In future distribution grids,there will be significant advances in operating strategies of SPV systems with the introduction of smart inverter functions.The new IEEE Std.1547-2018 incorporates dynamic Volt/VAr control(VVC)for smart inverters.These smart inverters can inject or absorb reactive power and maintain voltages at points of common coupling(PCCs)based on local voltage measurements.With multiple inverter-interfaced SPV systems connected to the grid,it becomes a necessary task to develop local,distributed or hybrid VVC algorithms for maximization of energy savings.This paper aims to estimate substation energy savings through centralized and decentralized control of inverters of SPV system alongside various VVC devices.Control strategies of each SPV inverter have been accomplished in compliance with IEEE Std.1547-2018.Time-series simulations are carried out on the modified IEEE-123 node test system.By utilizing smart inverters in traditional SPV systems,considerable energy savings can be obtained.These savings can be further increased by incorporating optimal intelligent VVC characteristics(IVVCC).Results show that just by allowing smart inverters on a predefined IVVCC(as per IEEE Std.1547-2018),a reduction of 11.69%in reactive demand and 5.63%in active demand have been acquired when compared with a conventional SPV system.Reactive energy demand is additionally reduced to 48.42%by considering centralized control of VVC devices alongside optimal IVVCC.展开更多
The regioselective acylation of quercetin catalyzed by a novel thermophilic esterase（APE1547） from the archaeon Aeropyrum pernix K1 was successfully conducted in organic solvents.The effects of acyl donor,substrate ...The regioselective acylation of quercetin catalyzed by a novel thermophilic esterase（APE1547） from the archaeon Aeropyrum pernix K1 was successfully conducted in organic solvents.The effects of acyl donor,substrate ratio,organic solvent,temperature,and water activity were investigated.Under the optimum conditions,a yield of 74% for its mono ester could be achieved in the reaction for about 6 h.With the reaction time extending to about 30 h,the final conversion of quercetin was about 100% and three products were synthesized.展开更多
文摘Thermophilic esterase APE1547 from Aeropyrum pernix K1 contained a β-propeller with seven blades. There are three hydrogen bonding interactions(Thr127-Gly154,Leu182- Arg145-Glu122) between blades 3 and 4 in the β-propeller domain of the APE1547. To examine the role of these hydrogen bonds, we eliminated these three hydrogen bonds between blades 3 and 4, by site-directed mutagenesis. The analysis results of kinetics, thermostability and differential scanning calorimetry(DSC) of the mutants show that Kcat/Km value of each mutation increased, and stability decreased dramatically than wild-type protein. These results strongly suggest that the three specific hydrogen bonds played an important role on maintaining the stability and activity of the esterase APE1547.
基金Supported by the National Natural Science Foundation of China(Nos.30400081 and 20432010)
文摘Hyperthermophilic enzyme APE1547 is an extremely thermostable recombinant protein from thermophilic archaeon Aeropyrumpernix K1. The Tyr444 located in the catalytic domain adjacent to the catalytic amino acid Ser445 and formed hydrogen bond with Ile567. To study the effect of Tyr444 on the activity of APE1547, site-directed mutagenesis was applied. Two mutant enzymes T444S and T444G were created. Comparison of the mutant enzymes with wide enzyme, the thermostability of mutants T444S and T444G decreased by 10%-20%, but the catalytic efficiency of mutants toward pNPC8 and Ac-Leu-pNA increased 1.33 and 1.75 fold respectively. Molecular modeling shows that the elimination of hydrogen bond between Tyr444 and Ile567 is the cause of the decrease in thermostability and increase in catalytic efficiency. These observations suggest that Tyr444 plays an important role in the catalytic ability and thermostability of this enzyme.
文摘Power conditioner, that is responsible for electric power conversion, is a critical component used in many renewable energy power generation systems. Most of the electric power produced by distributed energy resources cannot directly import to utility network without power conversion. Meanwhile, power conversion may includes several different types, for example AC/DC, and DC/AC, which is realized by a variety types of power conditioners in the electric power system. Currently, many concerns are focused on the operation of these power conditioners used in distributed energy resources due to the worse designing may cause the terrible influence on safety and performance characteristic of distributed energy resources. The power quality and reliability of interconnected electric power network may be affected as well. In the view of this, IEEE standards board provides a uniform standard for interconnection of distributed resources with electric power systems. It provides requirements relevant to the performance, operation, testing, safety considerations, and maintenance of the interconnection. Based on the IEEE 1547 standard, this paper presents a test system for power conditioners that are used in distributed energy resources or other renewable energy applications. Some of the test items that described in IEEE 1547.1 relevant to interconnection issues can be realized by proposed test system.
文摘In the present scenario,many solar photovoltaic(SPV)systems have been installed in the distribution network,most of them are operating at the unity power factor,which does not provide any reactive power support.In future distribution grids,there will be significant advances in operating strategies of SPV systems with the introduction of smart inverter functions.The new IEEE Std.1547-2018 incorporates dynamic Volt/VAr control(VVC)for smart inverters.These smart inverters can inject or absorb reactive power and maintain voltages at points of common coupling(PCCs)based on local voltage measurements.With multiple inverter-interfaced SPV systems connected to the grid,it becomes a necessary task to develop local,distributed or hybrid VVC algorithms for maximization of energy savings.This paper aims to estimate substation energy savings through centralized and decentralized control of inverters of SPV system alongside various VVC devices.Control strategies of each SPV inverter have been accomplished in compliance with IEEE Std.1547-2018.Time-series simulations are carried out on the modified IEEE-123 node test system.By utilizing smart inverters in traditional SPV systems,considerable energy savings can be obtained.These savings can be further increased by incorporating optimal intelligent VVC characteristics(IVVCC).Results show that just by allowing smart inverters on a predefined IVVCC(as per IEEE Std.1547-2018),a reduction of 11.69%in reactive demand and 5.63%in active demand have been acquired when compared with a conventional SPV system.Reactive energy demand is additionally reduced to 48.42%by considering centralized control of VVC devices alongside optimal IVVCC.
基金Supported by the National Natural Science Foundation of China(Nos.31070708,21172093 and 20772046)the Natural Science Foundation of Jilin Province,China(No.201115038)
文摘The regioselective acylation of quercetin catalyzed by a novel thermophilic esterase（APE1547） from the archaeon Aeropyrum pernix K1 was successfully conducted in organic solvents.The effects of acyl donor,substrate ratio,organic solvent,temperature,and water activity were investigated.Under the optimum conditions,a yield of 74% for its mono ester could be achieved in the reaction for about 6 h.With the reaction time extending to about 30 h,the final conversion of quercetin was about 100% and three products were synthesized.
