Geometric and electronic properties of graphene modified by “external” N-containing groups

2014 ◽  
Vol 16 (38) ◽  
pp. 20749-20754 ◽  
Author(s):  
Xinde Wang ◽  
Qiuxia Cai ◽  
Guilin Zhuang ◽  
Xing Zhong ◽  
Donghai Mei ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Binding Site ◽  
Electronic Properties ◽  
Catalytic Site ◽  
Pyridine Derivatives ◽  
Geometric And Electronic Properties

Due to electron transfer fromortho-carbon to nitrogen, theortho-carbon is the most stable binding site between pyridine derivatives and graphene or the catalytic site for a lot of reactions.

Deformation of polyiodides in Cs2I8 crystals at high pressure

2021 ◽  
Vol 77 (6) ◽  
Author(s):  
Tomasz Poreba ◽  
Gaston Garbarino ◽  
Davide Comboni ◽  
Mohamed Mezouar
Keyword(s):  
High Pressure ◽  
Electron Transfer ◽  
Bulk Modulus ◽  
Electronic Properties ◽  
Supramolecular Architecture ◽  
Ambient Conditions ◽  
Electron Transfer Mechanism ◽  
Covalently Bonded ◽  
Potential Sources ◽  
High Bulk

Dicaesium octaiodide is composed of layers of zigzag polyiodide units (I8 2−) intercalated with caesium cations. Each I8 2− unit is built of two triiodides bridged with one diiodine molecules. This system was subjected to compression up to 5.9 GPa under hydrostatic conditions. Pressure alters the supramolecular architecture around I8 2−, leading to bending of the triiodide units away from their energetically preferred geometry (D ∞h). Short I2...I3 − contacts compress significantly, reaching lengths typical for the covalently bonded polyiodides. Unlike in reported structures at ambient conditions, pressure-induced catenation proceeds without symmetrization of the polyiodides, pointing to a different electron-transfer mechanism. The structure is shown to be half as compressible [B0 = 12.9 (4) GPa] than the similar CsI3 structure. The high bulk modulus is associated with higher I—I connectivity and a more compact cationic net, than in CsI3. The small discontinuity in the compressibility trend around 3 GPa suggests formation of more covalent I—I bonds. The potential sources of this discontinuity and its implication on the electronic properties of Cs2I8 are discussed.

Ficin: a cysteine proteinase with binding site-catalytic site signalling characteristics intermediate between those of papain and actinidin

1993 ◽  
Vol 21 (2) ◽  
pp. 216S-216S
Author(s):  
Manij PATEL ◽  
Mark P. THOMAS ◽  
Irfan S. KAYANI ◽  
Geoffrey W. MELLOR ◽  
Emrys W. THOMAS ◽  
...  
Keyword(s):  
Binding Site ◽  
Cysteine Proteinase ◽  
Catalytic Site

Molecular Modelling of the Interaction of Cyanoacrylate Inhibitors with Photosystem II Part 2. The Effect of Stereochemistry of Inhibitor Binding

1993 ◽  
Vol 48 (9-10) ◽  
pp. 782-787 ◽  
Author(s):  
Simon P. Mackay ◽  
Patrick J. O’Malley
Keyword(s):  
Electron Transfer ◽  
Photosystem Ii ◽  
Binding Site ◽  
Energy Minimization ◽  
Electrostatic Interactions ◽  
D1 Protein ◽  
Spatial Arrangement ◽  
Inhibitor Binding ◽  
Protein Residues ◽  
Quinone Binding

Abstract The 2-cyanoacrylate inhibitors are a potent class of herbicides which block electron transfer in photosystem II. The spatial arrangement of different functional groups are an important factor in determining activity and a number of derivatives have been used as stereospecific probes of the secondary quinone binding site. More than one region of stereoselectivity in the binding site has been identified which influences the interaction with specific groups of the inhibitor. We have studied the interaction of various stereoisomers of the cyanoacrylates with the binding site in the D1 protein (residues Leu 210 to Val 280) by determining the nonbonded intermolecular energies between the modelled structures calculated by van der Waals and electrostatic interactions after energy minimization of the combined structures to reduce inter and intramolecular strain and have found that the results reflect the experimentally determined data

scholarly journals A specific oligosaccharide-binding site in the alternansucrase catalytic domain mediates alternan elongation

2020 ◽  
Vol 295 (28) ◽  
pp. 9474-9489 ◽  
Author(s):  
Manon Molina ◽  
Claire Moulis ◽  
Nelly Monties ◽  
David Guieysse ◽  
Sandrine Morel ◽  
...  
Keyword(s):  
Binding Site ◽  
Molar Mass ◽  
Enzyme Stability ◽  
Catalytic Site ◽  
Glycoside Hydrolase Family ◽  
Surface Binding ◽  
High Molar Mass ◽  
Sugar Binding ◽  
Binding Pockets ◽  
Domain V

Microbial α-glucans produced by GH70 (glycoside hydrolase family 70) glucansucrases are gaining importance because of the mild conditions for their synthesis from sucrose, their biodegradability, and their current and anticipated applications that largely depend on their molar mass. Focusing on the alternansucrase (ASR) from Leuconostoc citreum NRRL B-1355, a well-known glucansucrase catalyzing the synthesis of both high- and low-molar-mass alternans, we searched for structural traits in ASR that could be involved in the control of alternan elongation. The resolution of five crystal structures of a truncated ASR version (ASRΔ2) in complex with different gluco-oligosaccharides pinpointed key residues in binding sites located in the A and V domains of ASR. Biochemical characterization of three single mutants and three double mutants targeting the sugar-binding pockets identified in domain V revealed an involvement of this domain in alternan binding and elongation. More strikingly, we found an oligosaccharide-binding site at the surface of domain A, distant from the catalytic site and not previously identified in other glucansucrases. We named this site surface-binding site (SBS) A1. Among the residues lining the SBS-A1 site, two (Gln700 and Tyr717) promoted alternan elongation. Their substitution to alanine decreased high-molar-mass alternan yield by a third, without significantly impacting enzyme stability or specificity. We propose that the SBS-A1 site is unique to alternansucrase and appears to be designed to bind alternating structures, acting as a mediator between the catalytic site and the sugar-binding pockets of domain V and contributing to a processive elongation of alternan chains.

Electron transfer. 24. Catalysis of outer-sphere reactions by noncoordinated pyridine derivatives

1977 ◽  
Vol 99 (4) ◽  
pp. 1073-1077 ◽  
Author(s):  
Y. T. Fanchiang ◽  
R. R. Carlson ◽  
P. K. Thamburaj ◽  
Edwin S. Gould
Keyword(s):  
Electron Transfer ◽  
Outer Sphere ◽  
Pyridine Derivatives
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