scholarly journals Time-Resolved Studies of Ytterbium Distribution at Interfacial Surfaces of Ferritin-Like Dps Protein Demonstrate Metal Uptake and Storage Pathways

Biomedicines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 914
Author(s):  
Kornelius Zeth ◽  
Gabriela Pretre ◽  
Mitsuhiro Okuda
Keyword(s):  
Dynamic State ◽  
Structural Basis ◽  
Time Resolved ◽  
Static State ◽  
Metal Translocation ◽  
X Ray Crystallography ◽  
Ion Translocation ◽  
Multistep Process ◽  
Interfacial Surfaces ◽  
Dps Protein

Cage-shaped protein (CSP) complexes are frequently used in bionanotechnology, and they have a variety of different architectures and sizes. The smallest cage-shaped protein, Dps (DNA binding protein from starved cells), can naturally form iron oxide biominerals in a multistep process of ion attraction, translocation, oxidation, and nucleation. The structural basis of this biomineralization mechanism is still unclear. The aim of this paper is to further develop understanding of this topic. Time-resolved metal translocation of Yb3+ ions has been investigated on Dps surfaces using X-ray crystallography. The results reveal that the soak time of protein crystals with Yb3+ ions strongly affects metal positions during metal translocation, in particular, around and inside the ion translocation pore. We have trapped a dynamic state with ongoing translocation events and compared this to a static state, which is reached when the cavity of Dps is entirely filled by metal ions and translocation is therefore blocked. By comparison with La3+ and Co2+ datasets, the time-dependence together with the coordination sphere chemistry primarily determine metalprotein interactions. Our data can allow structure-based protein engineering to generate CSPs for the production of tailored nanoparticles.

scholarly journals Crystal structure of human carbonic anhydrase II at 1.95 Å resolution in complex with 667-coumate, a novel anti-cancer agent

2005 ◽  
Vol 385 (3) ◽  
pp. 715-720 ◽  
Author(s):  
Matthew D. LLOYD ◽  
Richard L. PEDERICK ◽  
Ramanathan NATESH ◽  
L. W. Lawrence WOO ◽  
Atul PUROHIT ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Phase 1 ◽  
Structural Basis ◽  
Pharmacokinetic Studies ◽  
Reversible Binding ◽  
X Ray Crystallography ◽  
Hydrophobic Binding ◽  
Cancer Agent

CA (carbonic anhydrase) catalyses the reversible hydration of carbon dioxide into bicarbonate, and at least 14 isoforms have been identified in vertebrates. The role of CA type II in maintaining the fluid and pH balance has made it an attractive drug target for the treatment of glaucoma and cancer. 667-Coumate is a potent inhibitor of the novel oncology target steroid sulphatase and is currently in Phase 1 clinical trials for hormone-dependent breast cancer. It also inhibits CA II in vitro. In the present study, CA II was crystallized with 667-coumate and the structure was determined by X-ray crystallography at 1.95 Å (1 Å=0.1 nm) resolution. The structure reported here is the first for an inhibitor based on a coumarin ring and shows ligation of the sulphamate group to the active-site zinc at 2.15 Å through a nitrogen anion. The first two rings of the coumarin moiety are bound within the hydrophobic binding site of CA II. Important residues contributing to binding include Val-121, Phe-131, Val-135, Leu-141, Leu-198 and Pro-202. The third seven-membered ring is more mobile and is located in the channel leading to the surface of the enzyme. Pharmacokinetic studies show enhanced stability of 667-coumate in vivo and this has been ascribed to binding of CA II in erythrocytes. This result provides a structural basis for the stabilization and long half-life of 667-coumate in blood compared with its rapid disappearance in plasma, and suggests that reversible binding of inhibitors to CA may be a general method of delivering this type of labile drug.

Increase of energy efficiency ratio of a direct evaporative cooler by dynamic behavior with energy and exergy analysis

2021 ◽  
pp. 095440622110420
Author(s):  
Behzad Omidi Kashani
Keyword(s):  
Energy Efficiency ◽  
Electrical Energy ◽  
Coefficient Of Performance ◽  
Dynamic State ◽  
Circulation Rate ◽  
Cooling Load ◽  
Efficiency Ratio ◽  
Static State ◽  
Circulation Pump ◽  
Water Rate

The present research is about increasing the energy efficiency ratio (EER) in current direct evaporative coolers (DEC) in Iran. Increasing the cooling load and reducing the electrical energy consumption simultaneously (increasing the energy efficiency ratio (EER)) in DEC are the main goals of manufacturers and consumers of this device. When the circulation water pump runs continuously (static state), the circulation water rate is about 1.89 to 2.90 times of the amounts recommended in the reasonable standards. In order to adjust the circulation water rate to the recommended amount by standards, the present study has utilized repetitive cyclic scheduling programs to reduce the circulation rate to the optimal amount, (by turning the circulation pump on and off by dynamic pattern operation). In other words, the circulation pump stays on only for a certain period of a working cycle, and then the pump stays off for the rest of it. The cooling load and EER were measured based on ASHRAE 133 (2015). The results indicated that the cooling load in the dynamic state increased by 5.03 and 6.18 percent compared to the static state at low and high fan speeds, respectively. Moreover, in comparison with the static state, the amount of electrical energy consumed (kW-hr) in the dynamic state decreased by 8.8 and 4.2 percent at low and high fan speeds, respectively. Finally, the coefficient of performance (COP or EER) of the DEC in the dynamic state is increased by 15.16 and 10.78 in comparison with the static state at low and high fan speeds, respectively.

A flow cell suitable for time-resolved X-ray crystallography by the Laue method

1997 ◽  
Vol 30 (5) ◽  
pp. 555-556 ◽  
Author(s):  
G. Kurisu ◽  
A. Sugimoto ◽  
Y. Kai ◽  
S. Harada
Keyword(s):  
Flow Cell ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Crystallography ◽  
Laue Method

Effects of Additives in KOH Based Electrolytes on Cu ECMP

2007 ◽  
Vol 991 ◽  
Author(s):  
Tae-Young Kwon ◽  
In-Kwon Kim ◽  
Jin-Goo Park
Keyword(s):  
Citric Acid ◽  
Applied Voltage ◽  
Counter Electrode ◽  
Corrosion Potential ◽  
Removal Rate ◽  
Chemical Mechanical Planarization ◽  
Corrosion Current ◽  
Dynamic State ◽  
Static State ◽  
Potentiodynamic Curves

ABSTRACTThe purpose of this study was to characterize KOH based electrolytes and effects of additives on electro-chemical mechanical planarization. The electrochemical mechanical polisher was made to measure the potentiodynamic curve and removal rate of Cu. The potentiodynamic curves were measured in static and dynamic states in investigated electrolytes using a potentiostat. Cu disk of 2 inch was used as a working electrode and Pt electroplated platen was used as a counter electrode. KOH was used as the electrolyte. H2O2 and citric acid were used as additives for the ECMP of Cu. In static and dynamic potentiodynamic measurements, the corrosion potential decreased and corrosion current increased as a function of KOH concentration. In dynamic state, different potentiodynamic curve was obtained when compared to the static state. The current density did not decrease in passivation region by mechanical polishing effect. The static etch and removal rate were measured as function of KOH concentration and applied voltage. In ECMP system, polishing was performed at 30 rpm and 1 psi. The removal rate was about 60 nm/min at 0.3 V when 5 wt% KOH was used. Also, the effect of additive was investigated in KOH based electrolyte on removal rates. As a result, The removal rate was increased to 350 nm/min when 5wt% KOH, 5vol% H2O2, 0.3 M citric acid were used.

Biomolecular dynamics: A report from a workshop in Gysinge, Sweden, October 4–7, 1982

1984 ◽  
Vol 17 (2) ◽  
pp. 125-151 ◽  
Author(s):  
Olle Edholm ◽  
Lennart Nilsson ◽  
Otto Berg ◽  
Måns Ehrenberg ◽  
Flora Claesens ◽  
...  
Keyword(s):  
Waller Factor ◽  
Biological Macromolecules ◽  
Time Resolved ◽  
X Ray Crystallography ◽  
Biomolecular Dynamics ◽  
Debye Waller Factor ◽  
Membrane Components ◽  
Theoretical Simulations ◽  
Structure Of Proteins ◽  
Molecular Picture

From the results of X-ray crystallography a wealth of information is now available concerning the detailed molecular structure of proteins, nucleic acids, and membrane components. This has made it possible to apply successfully various spectroscopie techniques for time resolved studies as well as theoretical simulations of internal molecular dynamics in the biological macromolecules and molecular aggregates. We were particularly pleased to see professor Ivar Waller among the participants of the workshop since new use of the wellknown Debye–Waller factor has greatly contributed to this development. A molecular picture is presently emerging including the dimension of time which ultimately will give us a detailed understanding of the functional interactions between biomolecules in general, and in particular enzyme catalysis, nucleic acid functions, and transport of matter and information through membranes.

scholarly journals The Geometry of the Catalytic Active Site in [FeFe]-Hydrogenases is Determined by Hydrogen Bonding and Proton Transfer

2019 ◽  
Author(s):  
Jifu Duan ◽  
Stefan Mebs ◽  
Moritz Senger ◽  
Konstantin Laun ◽  
Florian Wittkamp ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Proton Transfer ◽  
Active Site ◽  
Time Resolved ◽  
X Ray Crystallography ◽  
Hydrogen Bonding Interactions ◽  
Catalytic Active Site ◽  
Catalytic Intermediates ◽  
Time Resolved Infrared Spectroscopy

The H2 conversion and CO inhibition reactivity of nine [FeFe]-hydrogenase constructs with semi-artificial cofactors was studied by in situ and time-resolved infrared spectroscopy, X-ray crystallography, and theoretical methods. Impaired hydrogen turnover and proton transfer as well as characteristic CO inhibition/ reactivation kinetics are assigned to varying degrees of hydrogen-bonding interactions at the active site. We show that the probability to adopt catalytic intermediates is modulated by intramolecular and protein-cofactor interactions that govern structural dynamics at the active site of [FeFe]-hydrogenases.<br>

scholarly journals The Geometry of the Catalytic Active Site in [FeFe]-Hydrogenases is Determined by Hydrogen Bonding and Proton Transfer

2019 ◽  
Author(s):  
Jifu Duan ◽  
Stefan Mebs ◽  
Moritz Senger ◽  
Konstantin Laun ◽  
Florian Wittkamp ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Proton Transfer ◽  
Active Site ◽  
Time Resolved ◽  
X Ray Crystallography ◽  
Hydrogen Bonding Interactions ◽  
Catalytic Active Site ◽  
Catalytic Intermediates ◽  
Time Resolved Infrared Spectroscopy

The H2 conversion and CO inhibition reactivity of nine [FeFe]-hydrogenase constructs with semi-artificial cofactors was studied by in situ and time-resolved infrared spectroscopy, X-ray crystallography, and theoretical methods. Impaired hydrogen turnover and proton transfer as well as characteristic CO inhibition/ reactivation kinetics are assigned to varying degrees of hydrogen-bonding interactions at the active site. We show that the probability to adopt catalytic intermediates is modulated by intramolecular and protein-cofactor interactions that govern structural dynamics at the active site of [FeFe]-hydrogenases.<br>

State Estimation of Active Distribution Networks

2020 ◽  
pp. 270-308
Author(s):  
Razan Al Rhia ◽  
Haithm Daghrour
Keyword(s):  
State Estimation ◽  
Distribution System ◽  
Distribution Systems ◽  
Operating Performance ◽  
Distribution Networks ◽  
Dynamic State ◽  
State Estimator ◽  
Static State ◽  
Active Distribution Networks

Monitoring and controlling the electrical distribution system for real time is becoming very important to improve its operating performance after transition to active distribution systems. So, many sensors are needed to monitor all parts in the systems. But if sensors are installed at all buses, investment cost becomes huge. To reduce the number of sensors, state estimation approach can be used to estimate the voltage of buses, which do not have sensors. State Estimation (SE) algorithms are broadly classified into Static State Estimator (SSE) and Dynamic State Estimator (DSE). This chapter classifies most algorithms used in active distribution networks, also State estimation in unbalanced distribution systems, and Role of PMU in Distribution System State Estimation.

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