Lassa virus glycoprotein is synthesized as precursor GP-C into the lumen of the endoplasmic reticulum and cleaved posttranslationally into the N-terminal subunit GP-1 and the C-terminal subunit GP-2 ...by subtilase SKI-1/S1P. The N-terminal portion of the primary translation product preGP-C contains a signal peptide of unknown length. In order to demonstrate the signal peptide cleavage site, purified viral GP-1 isolated from Lassa virus particles was N-terminally sequenced as TSLYKGV, identical to amino acids 59–65 of GP-C. Mutational analysis of the amino acid residues flanking the putative cleavage site led to non-cleavable preGP-C indicating that no other signal peptide cleavage site exists. Interestingly, GP-C mutants with a non-cleavable signal peptide were not further processed by SKI-1/S1P. This observation suggests that the signal peptide cleavage is necessary for GP-C maturation and hence for Lassa virus replication.
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BFBNIB, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Hassium, element 108, was produced in the fusion reaction between
Mg and
Cm. The hassium recoils were oxidized
to a highly volatile oxide, presumably HsO
, and were transported in a mixture of He and ...O
to a deposition and detection system. The latter consisted of 16 silicon PIN-photodiodes facing a layer of NaOH, which served, in the presence of a certain partial pressure of water in the transport gas, as reactive surface for the deposition of the volatile tetroxides. Six correlated α-decay chains of Hs were detected in the first 5 detectors centred around detection position 3. In analogy to OsO
, which forms Na
OsO
(OH)
, an osmate(VIII), with aqueous NaOH, HsO
presumably was deposited as Na
HsO
(OH)
, a hassate(VIII).
The chloride and oxychloride chemistry of the group 7 elements Tc and Re was investigated in order to develop an experimental approach to a gas chemical characterisation of bohrium (Bh, element 107). ...In thermochromatography experiments with trace amounts of
Tc and
Re the formation of one volatile compound was observed in O
/HCl containing carrier gas, which was attributed to MO
Cl (M = Tc, Re). From the measured deposition temperatures the adsorption enthalpies on quartz surfaces ΔH
(TcO
Cl) = -51 ± 3 kJ/mol and ΔH
(ReO
Cl) = -62 ± 3 kJ/mol were evaluated. The sublimation enthalpies were derived using an empirical correlation between Δ H
and ΔH
: ΔH
(TcO
Cl) = 49±10 kJ/mol and ΔH
(ReO
Cl) = 67±10 kJ/mol. A fast gas chemical separation technique for highly volatile compounds of short-lived isotopes based on isothermal gas solid adsorption chromatography (OLGA-principle) was developed. With a modified OLGA device, model studies with the short-lived nuclides
Tc and
Re were carried out in preparation of an experimental gas chemical investigation of bohrium (Bh, element 107). Separation times of less than 3 s were achieved. A good separation of the oxychlorides of group 7 elements from chloride and oxychloride compounds of
Er,
Ho (as models for actinide elements),
Nb,
Zr (as models for light transactinide elements),
Po, and
Bi was accomplished in this chemical system.
During the last decade, a number of related bacterial membrane-bound multihaem c-type cytochromes, collectively referred to as the NapC/NirT family, were identified. These proteins are generally ...thought to catalyse electron transport between the quinone/quinol pool and periplasmic oxidoreductases. The best-characterized members, the tetrahaem c-type cytochromes NrfH and NapC, mediate electron transport to NrfA and NapA respectively. Amino acid sequence alignments suggest that the nature and position of distal haem c iron ligands differs in NrfH and NapC proteins. Site-directed modification of potential haem c iron-ligating histidine, lysine and methionine residues in Wolinella succinogenes NrfH was performed to determine the implication in electron transport from formate to nitrite. Two histidine, one lysine and one methionine residues were found to be essential, whereas the replacement of three other conserved histidine residues, one methionine and two lysines did not prevent growth by nitrite respiration. The results contrast those previously obtained for Paracoccus pantotrophus NapC, in which four essential histidine residues have been identified that are highly likely to serve as distal haem c iron ligands. The combined experimental evidence suggests different haem ligation patterns within NapC and NrfH proteins, which might reflect their different functions in the bacterial electron transfer.
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•DNA chemistry.•Density Functional Theory and SM8 Universal Solvation Model.•Vertical ionization potential and aqueous photoionization energy.•Bulk hydration vs. ...micro-hydration.•Activation energies of guanine methylation.
Results from DFT calculations indicate that states originating from gas-phase ionization of the phosphate and the base are degenerate in syn-5′-dGMP– and that bulk hydration lowers the base-localized ionization energy by <0.5eV. Local ionization maps show that micro-hydration leads to the formation of donor and acceptor hydrogen bonds and the ionization energy decreases or increases in each case respectively. The SN2 transition states of the methylation reactions of guanine with methane diazonium ions are lower at the N7 than at the O6 sites and they are influenced by local ionization energy and steric interference.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Abstract
Metallic catcher foils have been investigated on their thermal release capabilities for future superheavy element studies. These catcher materials shall serve as connection between ...production and chemical investigation of superheavy elements (SHE) at vacuum conditions. The diffusion constants and activation energies of diffusion have been extrapolated for various catcher materials using an atomic volume based model. Release rates can now be estimated for predefined experimental conditions using the determined diffusion values. The potential release behavior of the volatile SHE Cn (E112), E113, Fl (E114), E115, and Lv (E116) from polycrystalline, metallic foils of Ni, Y, Zr, Nb, Mo, Hf, Ta, and W is predicted. Example calculations showed that Zr is the best suited material in terms of on-line release efficiency and long-term operation stability. If higher temperatures up to 2773 K are applicable, tungsten is suggested to be the material of choice for such experiments.
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