A very long cobalt to nitrogen bond in a coenzyme B12 model. Relevance to the role of the 5,6-dimethylbenzimidazole in cobalt-carbon bond cleavage in coenzyme B12

1983 ◽  
Vol 105 (20) ◽  
pp. 6259-6263 ◽  
Author(s):  
Michael F. Summers ◽  
Paul J. Toscano ◽  
Nevenka Bresciani-Pahor ◽  
Giorgio Nardin ◽  
Lucio Randaccio ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Coenzyme B12 ◽  
Carbon Bond ◽  
Nitrogen Bond

Metal-Metal Cooperative Bond Activation by Heterobimetallic Alkyl, Aryl, and Acetylide PtII/CuI Complexes

2020 ◽  
Author(s):  
Shubham Deolka ◽  
Orestes Rivada Wheelaghan ◽  
Sandra Aristizábal ◽  
Robert Fayzullin ◽  
Shrinwantu Pal ◽  
...  
Keyword(s):  
Alkyl Group ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Terminal Alkyne ◽  
Alkyl Aryl ◽  
Metal Metal ◽  
The Stability ◽  
Selective Formation ◽  
Organoplatinum Compounds

We report selective formation of heterobimetallic PtII/CuI complexes that demonstrate how facile bond activation processes can be achieved by altering reactivity of common organoplatinum compounds through their interaction with another metal center. The interaction of the Cu center with Pt center and with a Pt-bound alkyl group increases the stability of PtMe2 towards undesired rollover cyclometalation. The presence of the CuI center also enables facile transmetalation from electron-deficient tetraarylborate [B(ArF)4]- anion and mild C-H bond cleavage of a terminal alkyne, which was not observed in the absence of an electrophilic Cu center. The DFT study indicates that the role of Cu center acts as a binding site for alkyne substrate, while activating its terminal C-H bond.

Mechanisms of ATP to cAMP Conversion Catalyzed by the Mammalian Adenylyl Cyclase: A Role of Magnesium Coordination Shells and Proton Wires

2019 ◽  
Author(s):  
Bella Grigorenko ◽  
Igor Polyakov ◽  
Alexander Nemukhin
Keyword(s):  
Adenylyl Cyclase ◽  
Bond Cleavage ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Md Simulations ◽  
Coordination Shell ◽  
Energy Profile ◽  
One Step ◽  
Type V

<p>We report a mechanism of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP) conversion by the mammalian type V adenylyl cyclase revealed in molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) simulations. We characterize a set of computationally derived enzyme-substrate (ES) structures showing an important role of coordination shells of magnesium ions in the solvent accessible active site. Several stable six-fold coordination shells of Mg<sub>A</sub><sup>2+ </sup>are observed in MD simulations of ES complexes. In the lowest energy ES conformation, the coordination shell of Mg<sub>A</sub><sup>2+ </sup>does not include the O<sub>δ1</sub> atom of the conserved Asp440 residue. Starting from this conformation, a one-step reaction mechanism is characterized which includes proton transfer from the ribose O<sup>3'</sup>H<sup>3' </sup>group in ATP to Asp440 via a shuttling water molecule and P<sup>A</sup>-O<sup>3A</sup> bond cleavage and O<sup>3'</sup>-P<sup>A</sup> bond formation. The energy profile of this route is consistent with the observed reaction kinetics. In a higher energy ES conformation, Mg<sub>A</sub><sup>2+</sup> is bound to the O<sub>δ1</sub>(Asp440) atom as suggested in the relevant crystal structure of the protein with a substrate analog. The computed energy profile initiated by this ES is characterized by higher energy expenses to complete the reaction. Consistently with experimental data, we show that the Asp440Ala mutant of the enzyme should exhibit a reduced but retained activity. All considered reaction pathways include proton wires from the O<sup>3'</sup>H<sup>3' </sup>group via shuttling water molecules. </p>

ChemInform Abstract: Iron-Catalyzed Synthesis of Glycine Derivatives via Carbon-Nitrogen Bond Cleavage Using Diazoacetate.

ChemInform ◽  
2011 ◽  
Vol 42 (14) ◽  
pp. no-no
Author(s):  
Yoichiro Kuninobu ◽  
Mitsumi Nishi ◽  
Kazuhiko Takai
Keyword(s):  
Bond Cleavage ◽  
Glycine Derivatives ◽  
Nitrogen Bond

Synthesis of 2-(Cyanomethyl)benzoic Esters via Carbon–Carbon Bond Cleavage of Indanones

2021 ◽  
Author(s):  
Xiangtai Meng ◽  
Dengfeng Chen ◽  
Rui Liu ◽  
Ping Jiang ◽  
Shenlin Huang
Keyword(s):  
Bond Cleavage ◽  
Carbon Bond ◽  
Carbon Carbon Bond
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