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1.
Laurens Kooijman Dr. Matthias Schuster Christian Baumann Simon Jurt Dr. Frank Löhr Dr. Boris Fürtig Prof. Dr. Peter Güntert Prof. Dr. Oliver Zerbe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21151-21158
To achieve efficient proton pumping in the light-driven proton pump bacteriorhodopsin (bR), the protein must be tightly coupled to the retinal to rapidly convert retinal isomerization into protein structural rearrangements. Methyl group dynamics of bR embedded in lipid nanodiscs were determined in the dark-adapted state, and were found to be mostly well ordered at the cytosolic side. Methyl groups in the M145A mutant of bR, which displays only 10 % residual proton pumping activity, are less well ordered, suggesting a link between side-chain dynamics on the cytosolic side of the bR cavity and proton pumping activity. In addition, slow conformational exchange, attributed to low frequency motions of aromatic rings, was indirectly observed for residues on the extracellular side of the bR cavity. This may be related to reorganization of the water network. These observations provide a detailed picture of previously undescribed equilibrium dynamics on different time scales for ground-state bR. 相似文献
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Steven D. Bull Simon W. Epstein Nadeam Mujtaba Edward D. Savory Juan A. Tamayo 《Tetrahedron》2006,62(33):7911-7925
Enolates of (S)-N,N′-bis-(p-methoxybenzyl)-3-iso-propylpiperazine-2,5-dione exhibit high levels of enantiodiscrimination in alkylations with (RS)-1-aryl-1-bromoethanes and (RS)-2-bromoesters, affording substituted diketopiperazines containing two new stereogenic centres in high de. Deprotection and hydrolysis of the resultant substituted diketopiperazines provides a route to the asymmetric synthesis of homochiral methyl 2-amino-3-aryl-butanoates and 3-methyl-aspartates in high de and ee. 相似文献
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In this paper we introduce a generalization of stable sets: stable multi-sets. A stable multi-set is an assignment of integers
to the vertices of a graph, such that specified bounds on vertices and edges are not exceeded. In case all vertex and edge
bounds equal one, stable multi-sets are equivalent to stable sets.
For the stable multi-set problem, we derive reduction rules and study the associated polytope. We state necessary and sufficient
conditions for the extreme points of the linear relaxation to be integer. These conditions generalize the conditions for the
stable set polytope. Moreover, the classes of odd cycle and clique inequalities for stable sets are generalized to stable
multi-sets and conditions for them to be facet defining are determined.
The study of stable multi-sets is initiated by optimization problems in the field of telecommunication networks. Stable multi-sets
emerge as an important substructure in the design of optical networks.
Received: February 14, 2001/Revised version: September 7, 2001 相似文献
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Dubrovin valuation rings and Henselization 总被引:4,自引:0,他引:4
Adrian R. Wadsworth 《Mathematische Annalen》1989,283(2):301-328
Supported in part by the National Science Foundation 相似文献
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