排序方式: 共有49条查询结果,搜索用时 177 毫秒
1.
Collot J Gradinaru J Humbert N Skander M Zocchi A Ward TR 《Journal of the American Chemical Society》2003,125(30):9030-9031
Homogeneous and enzymatic catalysis offer complementary means to generate enantiomerically pure compounds. Incorporation of achiral biotinylated rhodium-diphosphine complexes into (strept)avidin yields artificial metalloenzymes for the hydrogenation of N-protected dehydroamino acids. A chemogenetic optimization procedure allows one to produce (R)-acetamidoalanine with 96% enantioselectivity. These hybrid catalysts display features reminiscent both of enzymatic and of homogeneous systems. 相似文献
2.
Skander M Humbert N Collot J Gradinaru J Klein G Loosli A Sauser J Zocchi A Gilardoni F Ward TR 《Journal of the American Chemical Society》2004,126(44):14411-14418
We report on the generation of artificial metalloenzymes based on the noncovalent incorporation of biotinylated rhodium-diphosphine complexes in (strept)avidin as host proteins. A chemogenetic optimization procedure allows one to optimize the enantioselectivity for the reduction of acetamidoacrylic acid (up to 96% ee (R) in streptavidin S112G and up to 80% ee (S) in WT avidin). The association constant between a prototypical cationic biotinylated rhodium-diphosphine catalyst precursor and the host proteins was determined at neutral pH: log K(a) = 7.7 for avidin (pI = 10.4) and log K(a) = 7.1 for streptavidin (pI = 6.4). It is shown that the optimal operating conditions for the enantioselective reduction are 5 bar at 30 degrees C with a 1% catalyst loading. 相似文献
3.
Samy Skander Bahoura 《Comptes Rendus Mathematique》2005,341(1):25-28
We prove some a priori estimates in dimension for equations of type prescribed scalar curvature. In the particular case of the unit sphere we give an estimation of the constant c in the inequality . To cite this article: S. Skander Bahoura, C. R. Acad. Sci. Paris, Ser. I 341 (2005). 相似文献
4.
Adil Belhaj 《Physics letters. [Part B]》2011,705(5):539-542
Using D-brane physics, we study fractional quantum Hall solitons (FQHS) in ABJM-like theory in terms of type IIA dual geometries. In particular, we discuss a class of Chern-Simons (CS) quivers describing FQHS systems at low energy. These CS quivers come from R-R gauge fields interacting with D6-branes wrapped on 4-cycles, which reside within a blown up CP3 projective space. Based on the CS quiver method and mimicking the construction of del Pezzo surfaces in terms of CP2, we first give a model which corresponds to a single layer model of FQHS system, then we propose a multi-layer system generalizing the doubled CS field theory, which is used in the study of topological defect in graphene. 相似文献
5.
Adil Belhaj Luis J. Boya Antonio Segui 《International Journal of Theoretical Physics》2013,52(1):130-136
We analyze the geometrical background under which many Lie groups relevant to particle physics are endowed with a (possibly multiple) hexagonal structure. There are several groups appearing, either as special holonomy groups on the compactification process from higher dimensions, or as dynamical string gauge groups; this includes groups like SU(2), SU(3), G 2, Spin(7), O(8) as well as E 8 and O(32). We emphasize also the relation of these hexagonal structures with the octonion division algebra, as we expect as well eventually some role for octonions in the interpretation of symmetries in High Energy Physics. 相似文献
6.
Bouchra Belhaj Abdallah Ahmed Landoulsi Abdelwaheb Chatti 《Journal of Saudi Chemical Society》2018,22(1):110-118
The instant biosynthesis of silver nanoparticles under static electromagnetic induction, its antibacterial activity and its post exposure monitoring were reported here. A mix of silver nitrate solution and Ruta chalepensis leaf extract was irradiated by a static electromagnetic field (SMF) of 200 mT. The characteristics and stability of the biosynthesized silver nanoparticles (Ag NPs) were determined. Compared to the non-irradiated exposure, the morphology and state of the obtained material change once the exposition to SMF is turned off. Shifting from 453 to 473 nm, the percentage of the needles shaped silver nanoparticles increased and continue to win and dominate the biomixture toward the spherical silver nanoparticles. TEM microscopy showed a wide range of silver materials designed in different nanoscale morphology and beyond where they undergo major changes affecting mainly the size, shape and form (dispersity) of nanosilver. 相似文献
7.
Skander Belhaj 《Numerical Algorithms》2008,47(1):15-34
In this paper, we consider an approximate block diagonalization algorithm of an n×n real Hankel matrix in which the successive transformation matrices are upper triangular Toeplitz matrices, and propose a
new fast approach to compute the factorization in O(n
2) operations. This method consists on using the revised Bini method (Lin et al., Theor Comp Sci 315: 511–523, 2004). To motivate our approach, we also propose an approximate factorization variant of the customary fast method based on Schur
complementation adapted to the n×n real Hankel matrix. All algorithms have been implemented in Matlab and numerical results are included to illustrate the effectiveness
of our approach. 相似文献
8.
Samy Skander Bahoura 《Comptes Rendus Mathematique》2006,342(10):755-758
We give some results concerning inequalities for some elliptic operators of order 2 and 4. With those inequalities and the concentration phenomena we can describe the asymptotic behavior of those PDE solutions. To cite this article: S.S. Bahoura, C. R. Acad. Sci. Paris, Ser. I 342 (2006). 相似文献
9.
This article examines individual incentives to produce information on communication networks. In our setting, efforts are
strategic complements along communication paths with convex decay. We analyze the relationship between efforts and centrality
on a set of networks which are unambiguous in terms of ordinal centrality. We first show that in both dominant and dominated
equilibria central agents exert more effort. Second, we explore the issue of social coordination induced by our game. 相似文献
10.
Skander A. Abboud El hadji Cisse Michel Doudeau Hlne Bndetti Vincent Aucagne 《Chemical science》2021,12(9):3194
One of the main limitations encountered during the chemical synthesis of proteins through native chemical ligation (NCL) is the limited solubility of some of the peptide segments. The most commonly used solution to overcome this problem is to derivatize the segment with a temporary solubilizing tag. Conveniently, the tag can be introduced on the thioester segment in such a way that it is removed concomitantly with the NCL reaction. We herein describe a generalization of this approach to N-terminal cysteinyl segment counterparts, using a straightforward synthetic approach that can be easily automated from commercially available building blocks, and applied it to a well-known problematic target, SUMO-2.We herein describe a straightforward approach for the introduction of a solubilizing tag on N-terminal cysteinyl segments used in native chemical ligation-based protein chemical synthesis. Conveniently, the tag is removed during the ligation. 相似文献