Selenium-bridged diiron hexacarbonyl complexes as biomimetic models for the active site of Fe–Fe hydrogenases

2008 ◽  
pp. 2128 ◽  
Author(s):  
Shang Gao ◽  
Jiangli Fan ◽  
Shiguo Sun ◽  
Xiaojun Peng ◽  
Xing Zhao ◽  
...  
Keyword(s):  
Active Site ◽  
Biomimetic Models

scholarly journals Hydrogen Production Catalyzed by Bidirectional, Biomimetic Models of the [FeFe]-Hydrogenase Active Site

2014 ◽  
Vol 33 (20) ◽  
pp. 5897-5906 ◽  
Author(s):  
James C. Lansing ◽  
James M. Camara ◽  
Danielle E. Gray ◽  
Thomas B. Rauchfuss
Keyword(s):  
Hydrogen Production ◽  
Active Site ◽  
Biomimetic Models

Synthesis of biomimetic models of iron-only hydrogenases active site linked to Ru-polypyridine photosensitizers

2003 ◽  
Vol 96 (1) ◽  
pp. 57
Author(s):  
Licheng Sun ◽  
Sascha Oft ◽  
Szabolcs Salyi ◽  
Henriette Wolpher ◽  
Mikael Kritikos ◽  
...  
Keyword(s):  
Active Site ◽  
Biomimetic Models

Biomimetic Models for the Active Site of [Fe]Hydrogenase Featuring an Acylmethyl(hydroxymethyl)pyridine Ligand

2012 ◽  
Vol 51 (14) ◽  
pp. 7466-7468 ◽  
Author(s):  
Li-Cheng Song ◽  
Zhao-Jun Xie ◽  
Miao-Miao Wang ◽  
Gao-Yu Zhao ◽  
Hai-Bin Song
Keyword(s):  
Active Site ◽  
Pyridine Ligand ◽  
Biomimetic Models

Towards biomimetic models of the reduced [FeFe]-hydrogenase that preserve the key structural features of the enzyme active site; a DFT investigation

2014 ◽  
Vol 39 (32) ◽  
pp. 18565-18573 ◽  
Author(s):  
Sabrina Sicolo ◽  
Maurizio Bruschi ◽  
Luca Bertini ◽  
Giuseppe Zampella ◽  
Giulia Filippi ◽  
...  
Keyword(s):  
Active Site ◽  
Structural Features ◽  
Enzyme Active Site ◽  
Biomimetic Models

Locating Al in the DABCO catalyst before and after Al extraction

1990 ◽  
Vol 48 (4) ◽  
pp. 265-267
Author(s):  
Kathleen B. Reuter
Keyword(s):  
Active Site ◽  
Inverse Relationship ◽  
Transverse Direction ◽  
Reaction Rate ◽  
Acid Phosphate ◽  
Fracture Surfaces ◽  
Al Content ◽  
Before And After ◽  
Relationship Of

The reaction rate and efficiency of piperazine to 1,4-diazabicyclo-octane (DABCO) depends on the Si/Al ratio of the MFI topology catalysts. The Al was shown to be the active site, however, in the Si/Al range of 30-200 the reaction rate increases as the Si/Al ratio increases. The objective of this work was to determine the location and concentration of Al to explain this inverse relationship of Al content with reaction rate.Two silicalite catalysts in the form of 1/16 inch SiO2/Al2O3 bonded extrudates were examined: catalyst A with a Si/Al of 83; and catalyst B, the acid/phosphate Al extracted form of catalyst A, with a Si/Al of 175. Five extrudates from each catalyst were fractured in the transverse direction and particles were obtained from the fracture surfaces near the center of the extrudate diameter. Particles were also obtained from the outside surfaces of five extrudates.

Structures of c-di-GMP/cGAMP degrading phosphodiesterase VcEAL: identification of a novel conformational switch and its implication

2019 ◽  
Vol 476 (21) ◽  
pp. 3333-3353 ◽  
Author(s):  
Malti Yadav ◽  
Kamalendu Pal ◽  
Udayaditya Sen
Keyword(s):  
Active Site ◽  
Metal Binding ◽  
Metal Ion ◽  
Triosephosphate Isomerase ◽  
Catalytic Mechanism ◽  
Degradation Mechanism ◽  
Structural Basis ◽  
Conserved Residues ◽  
Phosphodiester Bond ◽  
Cyclic Dinucleotides

Cyclic dinucleotides (CDNs) have emerged as the central molecules that aid bacteria to adapt and thrive in changing environmental conditions. Therefore, tight regulation of intracellular CDN concentration by counteracting the action of dinucleotide cyclases and phosphodiesterases (PDEs) is critical. Here, we demonstrate that a putative stand-alone EAL domain PDE from Vibrio cholerae (VcEAL) is capable to degrade both the second messenger c-di-GMP and hybrid 3′3′-cyclic GMP–AMP (cGAMP). To unveil their degradation mechanism, we have determined high-resolution crystal structures of VcEAL with Ca2+, c-di-GMP-Ca2+, 5′-pGpG-Ca2+ and cGAMP-Ca2+, the latter provides the first structural basis of cGAMP hydrolysis. Structural studies reveal a typical triosephosphate isomerase barrel-fold with substrate c-di-GMP/cGAMP bound in an extended conformation. Highly conserved residues specifically bind the guanine base of c-di-GMP/cGAMP in the G2 site while the semi-conserved nature of residues at the G1 site could act as a specificity determinant. Two metal ions, co-ordinated with six stubbornly conserved residues and two non-bridging scissile phosphate oxygens of c-di-GMP/cGAMP, activate a water molecule for an in-line attack on the phosphodiester bond, supporting two-metal ion-based catalytic mechanism. PDE activity and biofilm assays of several prudently designed mutants collectively demonstrate that VcEAL active site is charge and size optimized. Intriguingly, in VcEAL-5′-pGpG-Ca2+ structure, β5–α5 loop adopts a novel conformation that along with conserved E131 creates a new metal-binding site. This novel conformation along with several subtle changes in the active site designate VcEAL-5′-pGpG-Ca2+ structure quite different from other 5′-pGpG bound structures reported earlier.

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