The regulation of nucleotide-regulated inorganic pyrophosphatases at a molecular level has been extensively studied in order to establish the mechanism of signal transduction between the active and ...regulatory sites of these enzymes. However, this issue cannot be ultimately addressed because of the lack of reliable structural data on the full-length protein and its interactions with ligands. The low-resolution structure of nucleotide-regulated pyrophosphatase from
Desulfitobacterium hafniense
was determined for the first time by small-angle X-ray scattering. The structural changes in the full-length enzyme upon binding of adenosine monophosphate and diadenosine tetraphosphate were revealed. In dilute solutions the protein was found to exist as a stable homotetramer, the structure of which depends on the nature of the bound ligand. The structural data are important for an understanding of the molecular basis for regulation of this family of enzymes.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Pyrophosphate regulates vital cellular reactions, and its level in
E. coli
cells is under the ultimate control of inorganic pyrophosphatase. The mechanisms involved in the regulation of ...pyrophosphatase activity still need to be elucidated. The present study demonstrated that fructose-1-phosphate inhibits pyrophosphatase activity by a mechanism not involving competition with substrate for binding to the active site. The inhibition constant governing the binding of the inhibitor to the enzyme–substrate complex is 1.1 mM. Substitutions of Lys112, Lys115, Lys148, and Arg43 in the regulatory site completely or partially abolished the inhibition. Thus, Fru-1-P is a physiological inhibitor of pyrophosphatase that acts via a regulatory site in this enzyme.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The paper describes the architecture of the behavioural analysis system in development. This system is directed to inner threat countering in computer systems through user behaviour analysis. A part ...of system's working algorithms is additionally presented together with the architecture. Also, next question is being decided - possibility of applying artificial neural networks for detection behavioural deviations instead comparing of statistical parameters.
The updated results of the precise measurements of the processes e+e−→ρ→π+π−, e+e−→ω→π+π−π0 and e+e−→φ→K0LK0S performed by the CMD-2 Collaboration are presented. The update appeared necessary due to ...an overestimate of the integrated luminosity in previous analyses.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK
The conditions for the onset of radiation equivalence of spent nuclear fuel from VVER and the equivalent mass of natural uranium according to the irradiation dose to organisms of surface ecosystems ...is investigated. It is found that organisms of soil biota receive the highest dose; mammals are the critical organisms for determining the requirements for wastes in terms of minimizing the onset time of radiation balance. The requirement for the onset of radiation balance in an acceptable time ~300 years can be met by separating from the spent nuclear fuel U, Pu, and Am with the residual amount in wastes no more than 0.1%. Radiation equivalence appears more quickly as the reactor run decreases or the depth of fuel burnup decreases. The results of this work confirm the main positions concerning radiation equivalence which were developed on the basis of comparative assessments of the biological hazard for man of the radionuclides present in the spent fuel and raw uranium.
The cross-section of the process e+e−→π+π− has been measured using about 114000 events collected by the CMD-2 detector at the VEPP-2M e+e− collider in the center-of-mass energy range from 0.61 to ...0.96 GeV. Results of the pion form factor determination with a 0.6% systematic uncertainty are presented. The following values of the ρ- and ω-meson parameters were found: Mρ=(776.09±0.81) MeV, Γρ=(144.46±1.55) MeV, Γ(ρ→e+e−)=(6.86±0.12) keV, Br(ω→π+π−)=(1.33±0.25)%. Implications for the hadronic contribution to the muon anomalous magnetic moment are discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK
The quasi-isentropic compressibilities of deuterium and helium plasmas are measured in the pressure range 1500–5000 GPa at densities up to 8 g/cm
3
using spherical experimental devices and an X-ray ...complex consisting of three betatrons and a multichannel optoelectronic system for taking X-ray images. The experimental results demonstrate the possibilities of high-energy-density experimental physics to reproduce the extreme states of substance typical of the Universe under laboratory conditions using the energy of traditional condensed explosives.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The T-15MD tokamak with the warm toroidal field coils, elongated plasma cross section, and a low aspect ratio was commissioned at the National Research Center Kurchatov Institute in 2021. An ...economically viable fusion reactor requires long discharges or even a steady-state mode. The short pulse of the toroidal field is among the main obstacles on the way to the steady state. Therefore, as a next step after T-15MD, it is proposed at the NRC Kurchatov Institute to consider the design of a superconducting tokamak (SCT), which holds the basic geometric parameters of the T-15MD:
R
/
a
= 1.5 m/0.67 m with a field on the axis of
B
0
< 5 T and a long pulse of current of
I
p
< 5 MA. The focus of the paper is the system of the toroidal magnetic field. A three-layer design of the toroidal field coil is proposed: an inner layer of a high-temperature superconductor (HTSC), a Nb
3
Sn middle layer, and a NbTi outer layer. On the basis of structural strength calculations, candidate materials for coil cases were selected. For cooling the coils, a semi-longitudinal pumping of low-pressure liquid helium is proposed. The design of the HTSC cable in conduit consisting of two halves is considered in detail. A mesh cryostat design that provides a convenient access for diagnostics and plasma heating is proposed. SCT systems similar to those used in the T-15MD are analyzed.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Using 3.07 pb
−1 of data collected in the energy range 0.60–0.97 GeV by CMD-2, about 150 events of the process e
+e
−→
π
+
π
−
π
+
π
− have been selected. The energy dependence of the cross section ...agrees with the assumption of the
a
1(1260)
π intermediate state which is dominant above 1 GeV. For the first time
π
+
π
−
π
+
π
− events are observed at the
ρ meson energy. Under the assumption that all these events come from the
ρ meson decay, the value of the cross section at the
ρ meson peak corresponds to the following decay width:
Γ(ρ
0→π
+π
−π
+π
−)=(2.8±1.4±0.5)
keV
or to the branching ratio
B(ρ
0→π
+π
−π
+π
−)=(1.8±0.9±0.3)·10
−5.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK
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