The characterization of cobalt molybdenum nitrides with various cobalt contents has been studied using XRD, TEM, XPS, and temperature-programmed reactions with NH3. The hydrodesulfurization of ...thiophene on the cobalt molybdenum nitride was carried out using a differential microreactor at atmospheric pressure. The XRD analysis of Co(50)973 indicated that Co3Mo3N was formed from the nitriding of a CoMoO4 precursor prepared from Co(NO3)2·6H2O and (NH4)6Mo7O24·4H2O but not from the mixture of CoO and MoO3. Co(10−25)973 had a high surface area of 120−129 m2 g-1, but Co(50)973 had that of 12 m2 g-1. The BET surface area was related to the molybdenum ions (Mo2+ and Mo3+) and cobalt ion (Co3+) in the bulk sample. The XPS and elemental analyses of Co(50)973 showed that the bulk composition was Co3Mo3N·N0.2 and the surface composition was Co3Mo3N·N2. The cobalt molybdenum nitride Co(0−35)973 was more active than cobalt molybdenum sulfide on basis of catalyst weight in the hydrodesulfurization of thiophene at 623 K.
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IJS, KILJ, NUK, PNG, UL, UM
Furin, PACE4, PC5/6 and PC7 are members of the subtilisin-like proprotein convertase (SPC) family. Although these enzymes are known to play critical roles in various physiological and pathological ...events including cell differentiation, tumor growth, virus replication and the activation of bacterial toxins, their distinct functions are yet to be fully delineated. alpha 1-PDX is an engineered alpha 1-antitrypsin variant carrying the RXXR consensus motif for furin within its reactive site loop. However, alpha 1-PDX inhibits other SPCs in addition to furin. In this work, we prepared various rat alpha 1-antitrypsin variants containing Arg at the P1 site within the reactive site loop, and examined their respective selectivity. The novel alpha 1-antitrypsin variant AVNR (AVPM super(352)/AVNR) was identified as a highly selective inhibitor of furin. This variant formed a sodium dodecyl sulfate- and heat-stable furin/ alpha 1-antitrypsin complex and inhibited furin activity ex vivo and in vitro. Other SPC members including PACE4, PC5/6 and PC7 were not inhibited by the AVNR variant. Furin-mediated maturation of bone morphogenetic protein-4 was completely inhibited by ectopic expression of the AVNR variant. The AVNR variant should prove to be a useful inhibitor in identifying the specific role of furin.
The crystal structure of the Alba protein (PhoAlba) from a hyperthermophilic archaeon, Pyrococcus horikoshii OT3, was determined at a resolution of 2.8 angstrom. PhoAlba structurally belongs to the ...alpha/beta proteins and is similar not only to archaeal homologues but also to RNA-binding proteins, including the C-terminal half of initiation factor 3 (IF3-C) from Bacillus stearothermophilus, an Escherichia coli protein implicated in cell division (Yhhp), and an Arabidopsis protein of unknown function. We found by gel shift assay that PhoAlba interacts with both ribonuclease P (RNase P) RNA (PhopRNA) and precursor-tRNAsup(Tyr)(pre-tRNAsup(Tyr)) in P. horikoshii. However, the addition of PhoAlba to reconstituted particles composed of PhopRNA and four or five protein subunits had little influence on either the pre-tRNA processing activity or the optimum temperature for the processing activity. These results suggest that PhoAlba contributes little to the catalytic activity of P. horikoshii RNase P.
The activities of the CoMo nitride catalysts, with and without sulfidation, were studied based on the rates of thiophene HDS per catalyst weight and turnover frequency (thiophene converted per ...irreversibly adsorbed CO). The surface properties, such as morphology, composition, and Co and Mo oxidation state numbers of the catalysts without exposure to air after nitriding were characterized by XRD, TEM, and temperature-programmed reduction. The CoMo nitride catalysts were used after nitriding during the temperature-programmed reaction of mixtures of MoO3 or (NH4)6Mo7O24·4H2O with CoO or Co(NO3)2·H2O with Co/(Co+Mo)=0, 0.25, and 0.5 in a stream of ammonia. Co3Mo3N was not produced by nitridation of a mixture of CoO and MoO3 but was produced from CoMoO4. The TEM analysis showed that Co3Mo3N particles (20 to 30 nm) were surrounded by γ-Mo2N particles (ca. 4 nm) in the catalyst nitrided at 1023 K. An XPS study without argon etching showed that the catalysts nitrided at 773 and 873 K contained Mo2+ and Co2+, while the catalysts nitrided at 973–1073 K mainly consisted of Mo0 and Co2+. The higher activity of the catalyst nitrided at 973 K compared to the other nitrided catalyst is probably due to the formation of a small amount of Co3Mo3N before the reaction and the obvious formation after the reaction. The sulfidation of the oxidic catalysts and the catalyst nitrided at 973 K produces stronger active sites of CoMo sulfide rather than Co3Mo3N for HDS.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The activated structure of RNase P RNA (PhopRNA) in Pyrococcus horikoshii OT3 was characterized by circular dichroism (CD) and ultraviolet (UV) absorbance spectra. The results suggested that ...interaction of four RNase P proteins (PhoPop5, PhoRpp21, PhoRpp29, and PhoRpp30) with PhopRNA results in destabilization of base stacking in PhopRNA, whereas the addition of a fifth protein, PhoRpp38, increases base stacking in PhopRNA.
The authors analyzed and compared 26 VLBI observations of the M87 jet, obtained between 2006 and 2011 with the Very Long Baseline Array at 1.7 GHz and the European VLBI Network at 5 GHz. HST-1 is ...detected at all epochs; they model-fitted its complex structure with two or more components, the two outermost of which display a significant proper motion with a superluminal velocity around similar to 4 c. The motion of a third feature that is detected upstream is more difficult to characterize. The overall position angle of HST-1 has changed during the time of our observations from -65 degree Celsius to -90 degree Celsius, while the structure has moved by over 80 mas downstream. Their results on the component evolution suggest that structural changes at the upstream edge of HST-1 can be related to the very high energy events.
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