scholarly journals Insights into the Maturation of Pernisine, a Subtilisin-Like Protease from the Hyperthermophilic Archaeon Aeropyrum pernix

2020 ◽  
Vol 86 (17) ◽  
Author(s):  
Miha Bahun ◽  
Marko Šnajder ◽  
Dušan Turk ◽  
Nataša Poklar Ulrih
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Catalytic Domain ◽  
Industrial Applications ◽  
Binding Motif ◽  
Content Type ◽  
Hyperthermophilic Archaeon ◽  
Aeropyrum Pernix ◽  
Autocatalytic Process ◽  
Exceptional Stability

ABSTRACT Pernisine is a subtilisin-like protease that was originally identified in the hyperthermophilic archaeon Aeropyrum pernix, which lives in extreme marine environments. Pernisine shows exceptional stability and activity due to the high-temperature conditions experienced by A. pernix. Pernisine is of interest for industrial purposes, as it is one of the few proteases that has demonstrated prion-degrading activity. Like other extracellular subtilisins, pernisine is synthesized in its inactive pro-form (pro-pernisine), which needs to undergo maturation to become proteolytically active. The maturation processes of mesophilic subtilisins have been investigated in detail; however, less is known about the maturation of their thermophilic homologs, such as pernisine. Here, we show that the structure of pro-pernisine is disordered in the absence of Ca2+ ions. In contrast to the mesophilic subtilisins, pro-pernisine requires Ca2+ ions to adopt the conformation suitable for its subsequent maturation. In addition to several Ca2+-binding sites that have been conserved from the thermostable Tk-subtilisin, pernisine has an additional insertion sequence with a Ca2+-binding motif. We demonstrate the importance of this insertion for efficient folding and stabilization of pernisine during its maturation. Moreover, analysis of the pernisine propeptide explains the high-temperature requirement for pro-pernisine maturation. Of note, the propeptide inhibits the pernisine catalytic domain more potently at high temperatures. After dissociation, the propeptide is destabilized at high temperatures only, which leads to its degradation and finally to pernisine activation. Our data provide new insights into and understanding of the thermostable subtilisin autoactivation mechanism. IMPORTANCE Enzymes from thermophilic organisms are of particular importance for use in industrial applications, due to their exceptional stability and activity. Pernisine, from the hyperthermophilic archaeon Aeropyrum pernix, is a proteolytic enzyme that can degrade infective prion proteins and thus has a potential use for disinfection of prion-contaminated surfaces. Like other subtilisin-like proteases, pernisine needs to mature through an autocatalytic process to become an active protease. In the present study, we address the maturation of pernisine and show that the process is regulated specifically at high temperatures by the propeptide. Furthermore, we demonstrate the importance of a unique Ca2+-binding insertion for stabilization of mature pernisine. Our results provide a novel understanding of thermostable subtilisin autoactivation, which might advance the development of these enzymes for commercial use.

High temperature mechanical properties of steel bars available in Pakistan

2018 ◽  
Vol 9 (3) ◽  
pp. 203-221 ◽  
Author(s):  
Muhammad Masood Rafi ◽  
Abdul Basit Dahar ◽  
Tariq Aziz
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Ambient Temperature ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Experimental Testing ◽  
Local Market ◽  
Content Type ◽  
Yield Plateau ◽  
Steel Bars

Purpose The purpose of this paper is to present the results of experimental testing of steel rebars at elevated temperatures. Three types of bars available in the local market in Pakistan were used. These data are not available in Pakistan. Design/methodology/approach Three types of bars were used, which included cold-twisted ribbed (CTR), hot-rolled deformed (HRD) and thermo-mechanically treated (TMT) bars. The diameter of the bar of each type was 16 mm. The bars were heated in an electrical furnace at temperatures which were varied from 100°C to 900°C in increment of 100°C. Bars of each type were also tested at ambient temperature as control specimens. The change of strength, strain and modulus of elasticity of the bars at high temperatures were determined. Findings The mechanical properties of the bars were nearly unaffected by the temperatures up to 200°C. CTR bars did not show yield plateau and strain hardening both at ambient and high temperatures. The high temperature yield strength and elastic modulus for all the three types of bars were similar at all temperatures. The yield plateau of both the HRD and TMT bars disappeared at temperatures greater than 300°C. The ultimate strength at high temperature of the HRD and TMT bars was also similar. The behaviours of the HRD and TMT bars changed to brittle beyond 400°C as compared to their behaviours at ambient temperature. The CTR bars exhibited ductile characteristics at failure at all the exposure temperatures relative to their behaviour at ambient temperature. Research limitations/implications The parameters of the paper included the rebar type and heating temperature and the effects of temperature on strength and stiffness properties of the steel bars. Practical implications Building fire incidents have increased in Pakistan. As reinforced concrete (RC) buildings exist in the country in significant numbers, the data related to elevated temperature properties of steel is required. These data are not available in Pakistan presently. The presented paper aims at providing this information for the design engineers to enable them to assess and increase fire resistance of RC structural members. Originality/value The presented paper is unique in its nature in that there is no published contribution to date, to the best of authors’ knowledge, which has been carried out to assess the temperature-dependent mechanical properties of steel reinforcing bars available in Pakistan.

High-transconductance silicon carbide nanowire-based field-effect transistor (SiC-NWFET) for high-temperature applications

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Habeeb Mousa ◽  
Kasif Teker
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Field Effect Transistor ◽  
High Electron ◽  
Si Substrate ◽  
Content Type ◽  
Nitrogen Doped ◽  
Sic Nanowires ◽  
Effect Transistor ◽  
High Transconductance

Purpose The purpose of this study is to present a systematic investigation of the effect of high temperatures on transport characteristics of nitrogen-doped silicon carbide nanowire-based field-effect transistor (SiC-NWFET). The 3C-SiC nanowires can endure high-temperature environments due to their wide bandgap, high thermal conductivity and outstanding physical and chemical properties. Design/methodology/approach The metal-organic chemical vapor deposition process was used to synthesize in-situ nitrogen-doped SiC nanowires on SiO2/Si substrate. To fabricate the proposed SiC-NWFET device, the dielectrophoresis method was used to integrate the grown nanowires on the surface of pre-patterned electrodes onto the SiO2 layer on a highly doped Si substrate. The transport properties of the fabricated device were evaluated at various temperatures ranging from 25°C to 350°C. Findings The SiC-NWFET device demonstrated an increase in conductance (from 0.43 mS to 1.2 mS) after applying a temperature of 150°C, and then a decrease in conductance (from 1.2 mS to 0.3 mS) with increasing the temperature to 350°C. The increase in conductance can be attributed to the thermionic emission and tunneling mechanisms, while the decrease can be attributed to the phonon scattering. Additionally, the device revealed high electron and hole mobilities, as well as very low resistivity values at both room temperature and high temperatures. Originality/value High-temperature transport properties (above 300°C) of 3C-SiC nanowires have not been reported yet. The SiC-NWFET demonstrates a high transconductance, high electron and hole mobilities, very low resistivity, as well as good stability at high temperatures. Therefore, this study could offer solutions not only for high-power but also for low-power circuit and sensing applications in high-temperature environments (∼350°C).

PE-RT: A New Class of Polyethylene for Industrial Pipes

2006 ◽  
Author(s):  
Detlef Schramm
Keyword(s):  
Molecular Structure ◽  
High Temperature ◽  
High Temperatures ◽  
Power Plants ◽  
Cold Water ◽  
Industrial Applications ◽  
Pipe Production ◽  
Term Strength ◽  
Temperature Resistance

The development of a new family of PE materials with significantly improved processability and long term strength at high temperatures is discussed. These polymers form the basis for a new ISO class of polyethylene materials: PE-RT (Polyethylene of Raised Temperature resistance) for hot and cold water as well as industrial pipe applications. These materials have a unique molecular structure and crystalline microstructure, which provides excellent Long Term Hydrostatic Strength at high temperature without crosslinking the material. PE-RT type materials are successfully used in domestic hot and cold water piping systems for most applications. The easy processing and outstanding material properties made these resins also attractive for use in many industrial applications, where larger dimensions are required and regular Polyethylene cannot be used or has temperature limitations. They also compete against high end engineering plastics, offering significant cost savings. These materials provide significant process advantages to the converters, allowing high line speed pipe production and providing excellent flexibility and ease of installation for the application. A recently developed PE-RT type material offers still higher long-term strength at high temperature and further improved processability. This combination makes this resin particularly suitable for high temperature applications. An example of the latter is in larger diameter cooling water pipes in power plants. Pipes based on these materials can be connected via heat welding or by the use of mechanical fittings. Furthermore this material can be used in industrial applications, were traditional Polyethylene is limited by the temperature resistance and metallic materials suffer from corrosion. The excellent weldability of these materials provides various opportunities to connect also larger dimensions in industrial applications. Another example of this is the use in multi-layer structured oil pipelines on-shore and off-shore. This paper presents the material science and product design concepts that govern the high long-term hydrostatic strength at high temperatures. By controlling the molecular structure, the melt rheology and solid state properties can be influenced. This results in a unique balance of processability and hydrostatic strength. Further discussed are the product features and benefits of PE-RT materials. The paper shows examples of the application range for this type of products, using applications in the domestic pipes market as a reference study.

scholarly journals Genome-Scale Metabolic Model of Caldicellulosiruptor bescii Reveals Optimal Metabolic Engineering Strategies for Bio-based Chemical Production

mSystems ◽  
2021 ◽  
Author(s):  
Ke Zhang ◽  
Weishu Zhao ◽  
Dmitry A. Rodionov ◽  
Gabriel M. Rubinstein ◽  
Diep N. Nguyen ◽  
...  
Keyword(s):  
Metabolic Engineering ◽  
High Temperatures ◽  
Plant Biomass ◽  
Metabolic Model ◽  
Industrial Applications ◽  
Cellulolytic Bacterium ◽  
Chemical Production ◽  
Content Type ◽  
Caldicellulosiruptor Bescii ◽  
Genome Scale

The extremely thermophilic cellulolytic bacterium, Caldicellulosiruptor bescii , degrades plant biomass at high temperatures without any pretreatments and can serve as a strategic platform for industrial applications. The metabolic engineering of C. bescii , however, faces potential bottlenecks in bio-based chemical productions.

High Temperature Dynamic Mechanical Properties Characterization of Polymer Coatings via Nanoindentation

2021 ◽  
pp. 1-17
Author(s):  
Yusuke Matsuda ◽  
Aref Samadi-Dooki ◽  
Yinjie Cen ◽  
Gisela Vazquez ◽  
Luke Bu
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperatures ◽  
Mechanical Response ◽  
Polymer Coatings ◽  
Dynamic Mechanical Properties ◽  
Industrial Applications ◽  
Dynamic Mechanical ◽  
Mechanical Properties Characterization

Abstract Polymer coatings are widely used in industrial applications. The mechanical properties of these polymer coatings are known to vary with temperature and deformation rate. The characterization of the dynamic mechanical properties of these coatings at high temperatures via traditional uniaxial testing is challenging due often to their brittleness and small size. In this paper, the mechanical properties of polymer coatings are reported with emphasis on their dynamic mechanical properties at temperatures up to 280 °C characterized by a dynamic nanoindentation technique with a sharp indenter tip. Nanoindentation was used to characterize the mechanical response with emphasis on dynamic mechanical properties of polymer coatings enclosed in a high-temperature stage. To verify the method, the viscoelastic properties of a reference PET were also characterized by uniaxial cyclic tensile testing which exhibited an excellent agreement with the proposed technique. The proposed nanoindentation method can be applied to other polymer coatings and thin films that are used in applications at high temperatures.

scholarly journals Distinct Modified Nucleosides in tRNATrp from the Hyperthermophilic Archaeon Thermococcus kodakarensis and Requirement of tRNA m2G10/m22G10 Methyltransferase (Archaeal Trm11) for Survival at High Temperatures

2019 ◽  
Vol 201 (21) ◽  
Author(s):  
Akira Hirata ◽  
Takeo Suzuki ◽  
Tomoko Nagano ◽  
Daishiro Fujii ◽  
Mizuki Okamoto ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
High Temperatures ◽  
Modified Nucleosides ◽  
Liquid Chromatography Mass Spectrometry ◽  
Content Type ◽  
Hyperthermophilic Archaeon ◽  
Thermococcus Kodakarensis ◽  
Chromatography Mass Spectrometry ◽  
Modified Nucleoside

ABSTRACT tRNA m2G10/m22G10 methyltransferase (archaeal Trm11) methylates the 2-amino group in guanosine at position 10 in tRNA and forms N2,N2-dimethylguanosine (m22G10) via N2-methylguanosine (m2G10). We determined the complete sequence of tRNATrp, one of the substrate tRNAs for archaeal Trm11 from Thermococcus kodakarensis, a hyperthermophilic archaeon. Liquid chromatography/mass spectrometry following enzymatic digestion of tRNATrp identified 15 types of modified nucleoside at 21 positions. Several modifications were found at novel positions in tRNA, including 2′-O-methylcytidine at position 6, 2-thiocytidine at position 17, 2′-O-methyluridine at position 20, 5,2′-O-dimethylcytidine at position 32, and 2′-O-methylguanosine at position 42. Furthermore, methylwyosine was found at position 37 in this tRNATrp, although 1-methylguanosine is generally found at this location in tRNATrp from other archaea. We constructed trm11 (Δtrm11) and some gene disruptant strains and compared their tRNATrp with that of the wild-type strain, which confirmed the absence of m22G10 and other corresponding modifications, respectively. The lack of 2-methylguanosine (m2G) at position 67 in the trm11 trm14 double disruptant strain suggested that this methylation is mediated by Trm14, which was previously identified as an m2G6 methyltransferase. The Δtrm11 strain grew poorly at 95°C, indicating that archaeal Trm11 is required for T. kodakarensis survival at high temperatures. The m22G10 modification might have effects on stabilization of tRNA and/or correct folding of tRNA at the high temperatures. Collectively, these results provide new clues to the function of modifications and the substrate specificities of modification enzymes in archaeal tRNA, enabling us to propose a strategy for tRNA stabilization of this archaeon at high temperatures. IMPORTANCE Thermococcus kodakarensis is a hyperthermophilic archaeon that can grow at 60 to 100°C. The sequence of tRNATrp from this archaeon was determined by liquid chromatography/mass spectrometry. Fifteen types of modified nucleoside were observed at 21 positions, including 5 modifications at novel positions; in addition, methylwyosine at position 37 was newly observed in an archaeal tRNATrp. The construction of trm11 (Δtrm11) and other gene disruptant strains confirmed the enzymes responsible for modifications in this tRNA. The lack of 2-methylguanosine (m2G) at position 67 in the trm11 trm14 double disruptant strain suggested that this position is methylated by Trm14, which was previously identified as an m2G6 methyltransferase. The Δtrm11 strain grew poorly at 95°C, indicating that archaeal Trm11 is required for T. kodakarensis survival at high temperatures.

scholarly journals Four Inserts within the Catalytic Domain Confer Extra Stability and Activity to Hyperthermostable Pyrolysin from Pyrococcus furiosus

2016 ◽  
Vol 83 (5) ◽  
Author(s):  
Xiaowei Gao ◽  
Jing Zeng ◽  
Huawei Yi ◽  
Fang Zhang ◽  
Bing Tang ◽  
...  
Keyword(s):  
High Temperatures ◽  
Calcium Binding ◽  
Catalytic Domain ◽  
Pyrococcus Furiosus ◽  
Ion Pairs ◽  
Structure Stability ◽  
Single Mutation ◽  
Structural Elements ◽  
Content Type ◽  
Enzyme Thermostability

ABSTRACT Pyrolysin from the hyperthermophilic archaeon Pyrococcus furiosus is the prototype of the pyrolysin family of the subtilisin-like serine protease superfamily (subtilases). It contains four inserts (IS147, IS29, IS27, and IS8) of unknown function in the catalytic domain. We performed domain deletions and showed that three inserts are either essential (IS147 and IS27) or important (IS8) for efficient maturation of pyrolysin at high temperatures, whereas IS29 is dispensable. The large insert IS147 contains Ca3 and Ca4, two calcium-binding Dx[DN]xDG motifs that are conserved in many pyrolysin-like proteases. Mutagenesis revealed that the Ca3 site contributes to enzyme thermostability and the Ca4 site is necessary for pyrolysin to fold into a maturation-competent conformation. Mature insert-deletion variants were characterized and showed that IS29 and IS8 contribute to enzyme activity and stability, respectively. In the presence of NaCl, pyrolysin undergoes autocleavage at two sites: one within IS29 and the other in IS27. Disrupting the ion pairs in IS27 and IS8 induces autocleavage in the absence of salts. Interestingly, autocleavage products combine noncovalently to form an active, nicked enzyme that is resistant to SDS and urea denaturation. Additionally, a single mutation in IS29 increases resistance to salt-induced autocleavage and further increases enzyme thermostability. Our results suggest that these extra structural elements play a crucial role in adapting pyrolysin to hyperthermal environments. IMPORTANCE Pyrolysin-like proteases belong to the subtilase superfamily and are characterized by large inserts and long C-terminal extensions; however, the role of the inserts in enzyme function is unclear. Our results demonstrate that four inserts in the catalytic domain of hyperthermostable pyrolysin contribute to the folding, maturation, stability, and activity of the enzyme at high temperatures. The modification of extra structural elements in pyrolysin-like proteases is a promising strategy for modulating global structure stability and enzymatic activity of this class of protease.

scholarly journals Characterization of a Novel Thermostable O-Acetylserine Sulfhydrylase from Aeropyrum pernix K1

2003 ◽  
Vol 185 (7) ◽  
pp. 2277-2284 ◽  
Author(s):  
Koshiki Mino ◽  
Kazuhiko Ishikawa
Keyword(s):  
Escherichia Coli ◽  
Rate Constant ◽  
Binding Motif ◽  
Phosphate Binding ◽  
Ph Optimum ◽  
Hyperthermophilic Archaeon ◽  
Aeropyrum Pernix ◽  
Synthetic Reaction

ABSTRACT An O-acetylserine sulfhydrylase (OASS) from the hyperthermophilic archaeon Aeropyrum pernix K1, which shares the pyridoxal 5′-phosphate binding motif with both OASS and cystathionine β-synthase (CBS), was cloned and expressed by using Escherichia coli Rosetta(DE3). The purified protein was a dimer and contained pyridoxal 5′-phosphate. It was shown to be an enzyme with CBS activity as well as OASS activity in vitro. The enzyme retained 90% of its activity after a 6-h incubation at 100°C. In the O-acetyl-l-serine sulfhydrylation reaction, it had a pH optimum of 6.7, apparent Km values for O-acetyl-l-serine and sulfide of 28 and below 0.2 mM, respectively, and a rate constant of 202 s−1. In the l-cystathionine synthetic reaction, it showed a broad pH optimum in the range of 8.1 to 8.8, apparent Km values for l-serine and l-homocysteine of 8 and 0.51 mM, respectively, and a rate constant of 0.7 s−1. A. pernix OASS has a high activity in the l-cysteine desulfurization reaction, which produces sulfide and S-(2,3-hydroxy-4-thiobutyl)-l-cysteine from l-cysteine and dithiothreitol.

scholarly journals Thermal Metamorphism on the Moon as Recorded by the Granulite Suite

2021 ◽  
pp. jgs2021-044
Author(s):  
John F. Pernet-Fisher ◽  
Katherine H. Joy
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Thermal Conditions ◽  
Heat Sources ◽  
The Moon ◽  
Lunar Crust ◽  
Content Type ◽  
Thermal Metamorphism ◽  
Lunar Meteorite ◽  
Supplementary Material

Thermally metamorphosed rocks on the Moon are an important, yet under-studied suite of lithologies that have been identified within the Apollo and lunar meteorite collections. These rocks, with granoblastic and poikilitic textures, are generally referred to as granulites. However, unlike their terrestrial counterparts which are the metamorphic products of both high temperatures and pressures, lunar granulites are thought to be the products of only high-temperature (> 1000 oC) thermal metamorphism that completely recrystallised their protoliths. We summarise the range of textures and chemical systematics reported from lunar granulites. These data enable constraints to be placed on the thermal conditions in the lunar crust required for high-temperature metamorphism to have taken place. Most studies indicate that impact melt sheets have the relevant thermal properties to sustain high temperatures over the time scales required to fully recrystallise surrounding crustal lithologies. However, the roles of alternative heat sources, such as magmatic intrusions into the crust, have not been extensively investigated and, as such, cannot be ruled out. Additionally, chemical data yields important insights into the protoliths of the granulite suite. By identifying protoliths, we greatly enhance our understanding of the range of lithologies that make up the primary lunar crust. In turn, this enables crustal formation models to be better constrained.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5623326

scholarly journals Scenario-based hazard analysis of extreme high-temperatures experienced between 1959 and 2014 in Hulunbuir, China

2019 ◽  
Vol 11 (1) ◽  
pp. 2-17
Author(s):  
Chunlan Li ◽  
Jun Wang ◽  
Min Liu ◽  
Desalegn Yayeh Ayal ◽  
Qian Gong ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Mitigation Strategies ◽  
Significant Feature ◽  
Environmental Damage ◽  
Fluctuation Analysis ◽  
Research Attention ◽  
Content Type ◽  
Extreme High Temperature ◽  
High Hazard

Purpose Extreme high temperatures are a significant feature of global climate change and have become more frequent and intense in recent years. These pose a significant threat to both human health and economic activity, and thus are receiving increasing research attention. Understanding the hazards posed by extreme high temperatures are important for selecting intervention measures targeted at reducing socioeconomic and environmental damage. Design/methodology/approach In this study, detrended fluctuation analysis is used to identify extreme high-temperature events, based on homogenized daily minimum and maximum temperatures from nine meteorological stations in a major grassland region, Hulunbuir, China, over the past 56 years. Findings Compared with the commonly used functions, Weibull distribution has been selected to simulate extreme high-temperature scenarios. It has been found that there was an increasing trend of extreme high temperature, and in addition, the probability of its indices increased significantly, with regional differences. The extreme high temperatures in four return periods exhibited an extreme low hazard in the central region of Hulunbuir, and increased from the center to the periphery. With the increased length of the return period, the area of high hazard and extreme high hazard increased. Topography and anomalous atmospheric circulation patterns may be the main factors influencing the occurrence of extreme high temperatures. Originality/value These results may contribute to a better insight in the hazard of extreme high temperatures, and facilitate the development of appropriate adaptation and mitigation strategies to cope with the adverse effects.

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