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141.
142.
The role of the GMP nucleotides of the bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor of the DMSO reductase family has long been a subject of discussion. The recent characterization of the bis-molybdopterin (bis-Mo-MPT) cofactor present in the E. coli YdhV protein, which differs from bis-MGD solely by the absence of the nucleotides, now enables studying the role of the nucleotides of bis-MGD and bis-MPT cofactors in Moco insertion and the activity of molybdoenzymes in direct comparison. Using the well-known E. coli TMAO reductase TorA as a model enzyme for cofactor insertion, we were able to show that the GMP nucleotides of bis-MGD are crucial for the insertion of the bis-MGD cofactor into apo-TorA. 相似文献
143.
Silicon‐ and Tin‐Containing Open‐Chain and Eight‐Membered‐Ring Compounds as Bicentric Lewis Acids toward Anions
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Dr. Anicet Siakam Wendji Dr. Christina Dietz Dr. Silke Kühn Michael Lutter Dr. Dieter Schollmeyer Dr. Wolf Hiller Prof. Dr. Klaus Jurkschat 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(1):404-416
Herein, we report the syntheses of silicon‐ and tin‐containing open‐chain and eight‐membered‐ring compounds Me2Si(CH2SnMe2X)2 ( 2 , X=Me; 3 , X=Cl; 4 , X=F), CH2(SnMe2CH2I)2 ( 7 ), CH2(SnMe2CH2Cl)2 ( 8 ), cyclo‐Me2Sn(CH2SnMe2CH2)2SiMe2 ( 6 ), cyclo‐(Me2SnCH2)4 ( 9 ), cyclo‐Me(2?n)XnSn(CH2SiMe2CH2)2SnXnMe(2?n) ( 5 , n=0; 10 , n = 1, X= Cl; 11 , n=1, X= F; 12 , n=2, X= Cl), and the chloride and fluoride complexes NEt4[cyclo‐ Me(Cl)Sn(CH2SiMe2CH2)2Sn(Cl)Me?F] ( 13 ), PPh4[cyclo‐Me(Cl)Sn(CH2SiMe2CH2)2Sn(Cl)Me?Cl] ( 14 ), NEt4[cyclo‐Me(F)Sn(CH2SiMe2CH2)2Sn(F)Me?F] ( 15 ), [NEt4]2[cyclo‐Cl2Sn(CH2SiMe2CH2)2SnCl2?2 Cl] ( 16 ), M[Me2Si(CH2Sn(Cl)Me2)2?Cl] ( 17 a , M=PPh4; 17 b , M=NEt4), NEt4[Me2Si(CH2Sn(Cl)Me2)2?F] ( 18 ), NEt4[Me2Si(CH2Sn(F)Me2)2?F] ( 19 ), and PPh4[Me2Si(CH2Sn(Cl)Me2)2?Br] ( 20 ). The compounds were characterised by electrospray mass‐spectrometric, IR and 1H, 13C, 19F, 29Si, and 119Sn NMR spectroscopic analysis, and, except for 15 and 18 , single‐crystal X‐ray diffraction studies. 相似文献
144.
145.
146.
How edge-reinforced random walk arises naturally 总被引:1,自引:0,他引:1
Silke W.W. Rolles 《Probability Theory and Related Fields》2003,126(2):243-260
We give a characterization of a modified edge-reinforced random walk in terms of certain partially exchangeable sequences.
In particular, we obtain a characterization of an edge-reinforced random walk (introduced by Coppersmith and Diaconis) on
a 2-edge-connected graph. Modifying the notion of partial exchangeability introduced by Diaconis and Freedman in [3], we characterize
unique mixtures of reversible Markov chains under a recurrence assumption.
Received: 22 January 2002 / Revised version: 24 September 2002
Published online: 15 April 2003
Most of this paper was written while the author was working at EURANDOM in Eindhoven, The Netherlands.
Mathematics Subject Classification (2000): 60K37, 60G09 相似文献
147.
148.
Silke I. Nitsche Edwin Weber Wilhelm Seichter Matyas Czugler Wolfram Palitzsch Gerhard Roewer 《Silicon Chemistry》2003,2(1-2):45-54
New organooligosiloxanes 1–5 (Scheme 1) featuring α ,ω -arylethynyl moieties have been synthesized. Complex ensembles of weak intramolecular interactions lead to the formation of interesting architectures, exhibiting the unusual U-shaped molecular geometry of compounds 1, 2 and 4, which has not been found previously example. Replacement of the methyl groups in 1 by phenyl substituents in the disiloxane 4 gives rise to the formation of hydrophobic monolayers different from the bilayer packing behavior of the analogous compound 1. Incorporation of methoxy substituted arene units in the α ,ω -positions completely abolishes intramolecular interactions as indicated in compound 5, which alsoshows the lowest degree of supramolecular contacts (while all the other packing structures are dominated by π -stacking andC-H···π interactions). 相似文献
149.
150.
A promising approach to the controlled synthesis of supported nanoparticles involves the use of molecular carbonyl clusters as precursors. Molecular metal clusters consist of a defined number of structurally ordered atoms, and active monodisperse metal particles are formed after dispersing the molecules and removing the ligands. An octanuclear palladium cluster precursor with easily displaceable ligands was used to generate palladium nanoparticles on mesoporous MCM-41. The molecular cluster precursor, [Pd8(CO)8(PMe3)7], was directly adsorbed from solution onto MCM-41, followed by gentle thermolysis which yielded small metal nanoparticles. Compared to MCM-41-based catalysts prepared from palladium salts by conventional methods, this cluster-derived palladium catalyst has shown an efficient activity for liquid-phase hydrogenation of alkenes. 相似文献