ChemInform Abstract: First Characterization of Zirconium Enolate Radical Cations in Solution and Their Mesolytic Bond Cleavage to Zirconocene Cations.

ChemInform ◽  
2010 ◽  
Vol 29 (25) ◽  
pp. no-no
Author(s):  
M. SCHMITTEL ◽  
R. SOELLNER
Keyword(s):  
Bond Cleavage ◽  
Radical Cations

A general synthesis approach in action: preparation and characterization of polyoxomolybdenum(vi) organophosphonates through oxidative Mo–Mo bond cleavage in {MoV2O4}

CrystEngComm ◽  
2012 ◽  
Vol 14 (14) ◽  
pp. 4826 ◽  
Author(s):  
Lijuan Zhang ◽  
Jingmei Sun ◽  
Yunshan Zhou ◽  
Sadaf ul Hassan ◽  
Enbo Wang ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Action Preparation ◽  
General Synthesis ◽  
Synthesis Approach

scholarly journals Unveiling the crucial intermediates in androgen production

2015 ◽  
Vol 112 (52) ◽  
pp. 15856-15861 ◽  
Author(s):  
Piotr J. Mak ◽  
Michael C. Gregory ◽  
Ilia G. Denisov ◽  
Stephen G. Sligar ◽  
James R. Kincaid
Keyword(s):  
Bond Cleavage ◽  
Nucleophilic Attack ◽  
Reaction Intermediates ◽  
Structural Determinants ◽  
Initial Product ◽  
Androgen Synthesis ◽  
Ferric Peroxo ◽  
Enzymatic Mechanisms ◽  
Primary Substrate

Ablation of androgen production through surgery is one strategy against prostate cancer, with the current focus placed on pharmaceutical intervention to restrict androgen synthesis selectively, an endeavor that could benefit from the enhanced understanding of enzymatic mechanisms that derives from characterization of key reaction intermediates. The multifunctional cytochrome P450 17A1 (CYP17A1) first catalyzes the typical hydroxylation of its primary substrate, pregnenolone (PREG) and then also orchestrates a remarkable C17–C20 bond cleavage (lyase) reaction, converting the 17-hydroxypregnenolone initial product to dehydroepiandrosterone, a process representing the first committed step in the biosynthesis of androgens. Now, we report the capture and structural characterization of intermediates produced during this lyase step: an initial peroxo-anion intermediate, poised for nucleophilic attack on the C20 position by a substrate-associated H-bond, and the crucial ferric peroxo-hemiacetal intermediate that precedes carbon–carbon (C-C) bond cleavage. These studies provide a rare glimpse at the actual structural determinants of a chemical transformation that carries profound physiological consequences.

scholarly journals Crystallization and preliminary X-ray characterization of the 2,4′-dihydroxyacetophenone dioxygenase fromAlcaligenessp. 4HAP

2014 ◽  
Vol 70 (6) ◽  
pp. 823-826 ◽  
Author(s):  
G. Beaven ◽  
A. Bowyer ◽  
P. Erskine ◽  
S. P. Wood ◽  
A. McCoy ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Formic Acid ◽  
Molecular Oxygen ◽  
Aromatic Ring ◽  
Bond Cleavage ◽  
Its Sequence ◽  
Hydroxybenzoic Acid ◽  
X Ray

The enzyme 2,4′-dihydroxyacetophenone dioxygenase (or DAD) catalyses the conversion of 2,4′-dihydroxyacetophenone to 4-hydroxybenzoic acid and formic acid with the incorporation of molecular oxygen. Whilst the vast majority of dioxygenases cleave within the aromatic ring of the substrate, DAD is very unusual in that it is involved in C—C bond cleavage in a substituent of the aromatic ring. There is evidence that the enzyme is a homotetramer of 20.3 kDa subunits each containing nonhaem iron and its sequence suggests that it belongs to the cupin family of dioxygenases. By the use of limited chymotrypsinolysis, the DAD enzyme fromAlcaligenessp. 4HAP has been crystallized in a form that diffracts synchrotron radiation to a resolution of 2.2 Å.

ChemInform Abstract: Mechanistic Aspects of β-Bond-Cleavage Reactions of Aromatic Radical Cations

ChemInform ◽  
2010 ◽  
Vol 31 (27) ◽  
pp. no-no
Author(s):  
Enrico Baciocchi ◽  
Massimo Bietti ◽  
Osvaldo Lanzalunga
Keyword(s):  
Bond Cleavage ◽  
Radical Cations ◽  
Aromatic Radical ◽  
Cleavage Reactions

scholarly journals Oxidation of End-Capped Pentathienoacenes and Characterization of Their Radical Cations

2009 ◽  
Vol 15 (45) ◽  
pp. 12346-12361 ◽  
Author(s):  
Reyes Malavé Osuna ◽  
M. Carmen Ruiz Delgado ◽  
Víctor Hernández ◽  
Juan T. López Navarrete ◽  
Barbara Vercelli ◽  
...  
Keyword(s):  
Radical Cations
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