scholarly journals [NiFe] Hydrogenase fromAlteromonas macleodiiwith Unusual Stability in the Presence of Oxygen and High Temperature

2011 ◽  
Vol 77 (6) ◽  
pp. 1990-1998 ◽  
Author(s):  
Walter A. Vargas ◽  
Philip D. Weyman ◽  
Yingkai Tong ◽  
Hamilton O. Smith ◽  
Qing Xu
Keyword(s):  
High Temperature ◽  
Alternative Energy ◽  
Marine Bacterium ◽  
Maximum Activity ◽  
Hydrogenase Activity ◽  
Potential Candidate ◽  
Hydrogen Deuterium ◽  
Membrane Bound ◽  
Posttranscriptional Level ◽  
Alteromonas Macleodii

ABSTRACTHydrogenases are enzymes involved in the bioproduction of hydrogen, a clean alternative energy source whose combustion generates water as the only end product. In this article we identified and characterized a [NiFe] hydrogenase from the marine bacteriumAlteromonas macleodii“deep ecotype” with unusual stability toward oxygen and high temperature. TheA. macleodiihydrogenase (HynSL) can catalyze both H2evolution and H2uptake reactions. HynSL was expressed inA. macleodiiunder aerobic conditions and reached the maximum activity when the cells entered the late exponential phase. The higher level of hydrogenase activity was accompanied by a greater abundance of the HynSL protein in the late-log or stationary phase. The addition of nickel to the growth medium significantly enhanced the hydrogenase activity. Ni treatment affected the level of the protein, but not the mRNA, indicating that the effect of Ni was exerted at the posttranscriptional level. Hydrogenase activity was distributed ∼30% in the membrane fraction and ∼70% in the cytoplasmic fraction. Thus, HynSL appears to be loosely membrane-bound. Partially purifiedA. macleodiihydrogenase demonstrated extraordinary stability. It retained 84% of its activity after exposure to 80°C for 2 h. After exposure to air for 45 days at 4°C, it retained nearly 100% of its activity when assayed under anaerobic conditions. Its catalytic activity in the presence of O2was evaluated by the hydrogen-deuterium (H-D) exchange assay. In 1% O2, 20.4% of its H-D exchange activity was retained. The great stability of HynSL makes it a potential candidate for biotechnological applications.

scholarly journals Identification and Biochemical Characterization of a Surfactant-Tolerant Chondroitinase VhChlABC from Vibrio hyugaensis LWW-1

Marine Drugs ◽  
2021 ◽  
Vol 19 (7) ◽  
pp. 399
Author(s):  
Juanjuan Su ◽  
Xiaoyi Wang ◽  
Chengying Yin ◽  
Yujiao Li ◽  
Hao Wu ◽  
...  
Keyword(s):  
Marine Bacterium ◽  
Biochemical Characterization ◽  
Maximum Activity ◽  
Potential Candidate ◽  
Good Tool ◽  
Polysaccharide Lyase ◽  
Candidate Drug ◽  
Wide Range ◽  
And Function

Chondroitinases, catalyzing the degradation of chondroitin sulfate (CS) into oligosaccharides, not only play a crucial role in understanding the structure and function of CS, but also have been reported as a potential candidate drug for the treatment of high CS-related diseases. Here, a marine bacterium Vibrio hyugaensis LWW-1 was isolated, and its genome was sequenced and annotated. A chondroitinase, VhChlABC, was found to belong to the second subfamily of polysaccharide lyase (PL) family 8. VhChlABC was recombinant expressed and characterized. It could specifically degrade CS-A, CS-B, and CS-C, and reached the maximum activity at pH 7.0 and 40 °C in the presence of 0.25 M NaCl. VhChlABC showed high stability within 8 h under 37 °C and within 2 h under 40 °C. VhChlABC was stable in a wide range of pH (5.0~10.6) at 4 °C. Unlike most chondroitinases, VhChlABC showed high surfactant tolerance, which might provide a good tool for removing extracellular CS proteoglycans (CSPGs) of lung cancer under the stress of pulmonary surfactant. VhChlABC completely degraded CS to disaccharide by the exolytic mode. This research expanded the research and application system of chondroitinases.

scholarly journals Draft Genome Sequences of Four Alteromonas macleodii Strains Isolated from Copper Coupons and Grown Long-Term at Elevated Copper Levels: TABLE 1 

2016 ◽  
Vol 4 (6) ◽  
Author(s):  
Kathleen D. Cusick ◽  
Jason R. Dale ◽  
Brenda J. Little ◽  
Justin C. Biffinger
Keyword(s):  
Marine Bacterium ◽  
Draft Genome ◽  
Genome Sequences ◽  
Ship Hulls ◽  
Early Stages ◽  
Antifouling Agent ◽  
Alteromonas Macleodii

Alteromonas macleodii is a marine bacterium involved in the early stages of biofouling on ship hulls treated with copper as an antifouling agent. We report here the draft genome sequences of an A. macleodii strain isolated from copper coupons and three laboratory mutants grown long-term at elevated copper levels.

High-Temperature PbTe Thin Films for Use in Cascade Thermoelectric Power Generation

2003 ◽  
Vol 793 ◽  
Author(s):  
J.B. Posthill ◽  
J.C. Caylor ◽  
P.D. Crocco ◽  
T.S. Colpitts ◽  
R. Venkatasubramanian
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Power Generation ◽  
High Temperature ◽  
Ambient Temperature ◽  
Thermoelectric Power ◽  
Thermal Evaporation ◽  
Potential Candidate ◽  
Substrate Orientation ◽  
Subtle Effect

ABSTRACTPbTe-based thin films were deposited by thermal evaporation at temperatures ranging from ambient temperature to 430°C on different vicinal GaAs (100) substrates and BaF2 (111). This materials system is being evaluated as a potential candidate thermoelectric material for a mid-temperature stage in a cascade power generation module. Pure PbTe, PbSe, and multilayer PbTe/PbSe films were investigated. All films deposited on different vicinal GaAs (100) substrates were found to be polycrystalline when deposited at 250°C or lower. A subtle effect of substrate orientation and multilayer periodicity appears to contribute to the more randomly oriented polycrystallinity, which also lowers the thermal conductivity. These results are compared with PbTe epitaxial results on BaF2 (111).

Pyrophosphate as an alternative energy currency in plants

2021 ◽  
Vol 478 (8) ◽  
pp. 1515-1524
Author(s):  
Abir U. Igamberdiev ◽  
Leszek A. Kleczkowski
Keyword(s):  
Metabolic Pathways ◽  
Energy Efficient ◽  
Alternative Energy ◽  
Plant Cells ◽  
Atp Synthesis ◽  
Continuous Operation ◽  
Low Oxygen ◽  
Pyruvate Phosphate Dikinase ◽  
Oxygen Stress ◽  
Membrane Bound

In the conditions of [Mg2+] elevation that occur, in particular, under low oxygen stress and are the consequence of the decrease in [ATP] and increase in [ADP] and [AMP], pyrophosphate (PPi) can function as an alternative energy currency in plant cells. In addition to its production by various metabolic pathways, PPi can be synthesized in the combined reactions of pyruvate, phosphate dikinase (PPDK) and pyruvate kinase (PK) by so-called PK/PPDK substrate cycle, and in the reverse reaction of membrane-bound H+-pyrophosphatase, which uses the energy of electrochemical gradients generated on tonoplast and plasma membrane. The PPi can then be consumed in its active forms of MgPPi and Mg2PPi by PPi-utilizing enzymes, which require an elevated [Mg2+]. This ensures a continuous operation of glycolysis in the conditions of suppressed ATP synthesis, keeping metabolism energy efficient and less dependent on ATP.

scholarly journals Derived high reducing sugar and lignin colloid particles from corn stover

BMC Chemistry ◽  
2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Wei Liu ◽  
Shengnan Zhuo ◽  
Mengying Si ◽  
Mengting Yuan ◽  
Yan Shi
Keyword(s):  
Corn Stover ◽  
Lignocellulosic Biomass ◽  
Alternative Energy ◽  
Reducing Sugar ◽  
Sugar Yield ◽  
Potential Candidate ◽  
Practical Utilization ◽  
Lignin Concentration ◽  
Colloid Particles ◽  
G Ratio

AbstractLignocellulosic biomass is considered as the largest potential candidate to develop alternative energy, such as biofuel, biomaterial. However, the efficient conversion of cellulose and practical utilization of lignin are great challenges for sustainable biorefinery. In this study, high reducing sugar yield and different size of lignin colloid particles (LCPs) were obtained via tetrahydrofuran–water (THF–H2O) pretreatment of corn stover (CS). THF–H2O as a co-solvent, could efficiently dissolve lignin and retain cellulose. After the pretreatment, 640.87 mg/g of reducing sugar was produced, that was 6.66-fold higher than that of the untreated CS. Meanwhile, the pretreatment liquor could form spherical LCPs with different sizes ranged from 202 to 732 nm through self-assembly. We studied the optimal pretreatment condition to simultaneously realize the high reducing sugar yield (588.4 mg/g) and excellent LCPs preparation with average size of 243 nm was under TH22 (THF–H2O pretreatment at 120 °C for 2 h). To further explore the formation of LCPs with different sizes. We studied the lignin structure changes of various conditions, concluded the size of LCPs was related to the lignin concentration and syringyl/guaiacyl (S/G) ratio. As the increase of the lignin concentration and S/G, the sizes of LCPs were increased. G-type lignin was easier to dissolve in the mild pretreatment supernatant, contributing to form smaller LCPs with a good dispersibility. In the severe condition, both of S and G-type lignin were dissolved due to the lignin depolymerization, formed the larger sphere particles. This work provides a novel perspective for the technical design of lignocellulosic biomass conversion.

scholarly journals Load-dependent destabilization of the γ-rotor shaft in FOF1 ATP synthase revealed by hydrogen/deuterium-exchange mass spectrometry

2016 ◽  
Vol 113 (9) ◽  
pp. 2412-2417 ◽  
Author(s):  
Siavash Vahidi ◽  
Yumin Bi ◽  
Stanley D. Dunn ◽  
Lars Konermann
Keyword(s):  
Mass Spectrometry ◽  
Molecular Motor ◽  
Conformational Dynamics ◽  
Bound State ◽  
Deuterium Exchange ◽  
Hydrogen Deuterium Exchange ◽  
Exchange Mass Spectrometry ◽  
Hydrogen Deuterium ◽  
Membrane Bound ◽  
Deuterium Exchange Mass Spectrometry

FoF1 is a membrane-bound molecular motor that uses proton-motive force (PMF) to drive the synthesis of ATP from ADP and Pi. Reverse operation generates PMF via ATP hydrolysis. Catalysis in either direction involves rotation of the γε shaft that connects the α3β3 head and the membrane-anchored cn ring. X-ray crystallography and other techniques have provided insights into the structure and function of FoF1 subcomplexes. However, interrogating the conformational dynamics of intact membrane-bound FoF1 during rotational catalysis has proven to be difficult. Here, we use hydrogen/deuterium exchange mass spectrometry to probe the inner workings of FoF1 in its natural membrane-bound state. A pronounced destabilization of the γ C-terminal helix during hydrolysis-driven rotation was observed. This behavior is attributed to torsional stress in γ, arising from γ⋅⋅⋅α3β3 interactions that cause resistance during γ rotation within the apical bearing. Intriguingly, we find that destabilization of γ occurs only when FoF1 operates against a PMF-induced torque; the effect disappears when PMF is eliminated by an uncoupler. This behavior resembles the properties of automotive engines, where bearings inflict greater forces on the crankshaft when operated under load than during idling.

scholarly journals On the high temperature phase transition in Ba(Zr0.20Ti0.80)O3 ceramic

2017 ◽  
Vol 07 (04) ◽  
pp. 1750025 ◽  
Author(s):  
K. P. Chandra ◽  
A. R. Kulkarni ◽  
K. Prasad
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Lattice Structure ◽  
High Temperature Phase ◽  
Monoclinic Space Group ◽  
Temperature Phase ◽  
Potential Candidate ◽  
Space Group ◽  
Structure Changes ◽  
Temperature Phase Transition

Temperature dependent X-ray diffraction (XRD) and dielectric properties of perovskite Ba(Zr[Formula: see text]Ti[Formula: see text]O3 ceramic prepared using a standard solid-state reaction process is presented. Along with phase transitions at low temperature, a new phase transition at high temperature (873[Formula: see text]C at 20[Formula: see text]Hz), diffusive in character has been found where the lattice structure changes from monoclinic (space group: [Formula: see text] to hexagonal (space group: [Formula: see text]). This result places present ceramic in the list of potential candidate for intended high temperature applications. The AC conductivity data followed hopping type charge conduction and supports jump relaxation model. The experimental value of [Formula: see text][Formula: see text]pC/N was found. The dependence of polarization and strain on electric field at room temperature suggested that lead-free Ba(Zr[Formula: see text]Ti[Formula: see text]O3 is a promising material for electrostrictive applications.

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