Theoretical Study on the Mechanism of the Oxygen Activation Process in Cysteine Dioxygenase Enzymes

2011 ◽  
Vol 133 (11) ◽  
pp. 3869-3882 ◽  
Author(s):  
Devesh Kumar ◽  
Walter Thiel ◽  
Sam P. de Visser
Keyword(s):  
Theoretical Study ◽  
Oxygen Activation ◽  
Activation Process ◽  
Cysteine Dioxygenase ◽  
Dioxygenase Enzymes

scholarly journals Asymmetric Cyanation of Activated Olefins with Ethyl Cyanoformate Catalyzed by Ti(IV)-Catalyst: A Theoretical Study

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1079
Author(s):  
Zhishan Su ◽  
Changwei Hu ◽  
Nasir Shahzad ◽  
Chan Kyung Kim
Keyword(s):  
Transition State ◽  
Self Assembly ◽  
Theoretical Study ◽  
Activation Barrier ◽  
Cinchona Alkaloid ◽  
Activation Process ◽  
Construction Step ◽  
Dual Activation ◽  
Membered Transition State ◽  
Step Mechanism

The reaction mechanism and origin of asymmetric induction for conjugate addition of cyanide to the C=C bond of olefin were investigated at the B3LYP-D3(BJ)/6-31+G**//B3LYP-D3(BJ)/6-31G**(SMD, toluene) theoretical level. The release of HCN from the reaction of ethyl cyanoformate (CNCOOEt) and isopropanol (HOiPr) was catalyzed by cinchona alkaloid catalyst. The cyanation reaction of olefin proceeded through a two-step mechanism, in which the C-C bond construction was followed by H-transfer to generate a cyanide adduct. For non-catalytic reaction, the activation barrier for the rate-determining C-H bond construction step was 34.2 kcal mol−1, via a four-membered transition state. The self-assembly Ti(IV)-catalyst from tetraisopropyl titanate, (R)-3,3′-disubstituted biphenol, and cinchonidine accelerated the addition of cyanide to the C=C double bond by a dual activation process, in which titanium cation acted as a Lewis acid to activate the olefin and HNC was orientated by hydrogen bonding. The steric repulsion between the 9-phenanthryl at the 3,3′-position in the biphenol ligand and the Ph group in olefin raised the Pauli energy (ΔE≠Pauli) of reacting fragments at the re-face attack transition state, leading to the predominant R-product.

The Mechanism of Cysteine Oxygenation by Cysteine Dioxygenase Enzymes

2007 ◽  
Vol 129 (48) ◽  
pp. 14846-14847 ◽  
Author(s):  
Swathi Aluri ◽  
Sam P. de Visser
Keyword(s):  
Cysteine Dioxygenase ◽  
Dioxygenase Enzymes

Theoretical study of cesium and oxygen activation processes on GaN (0001) surface

2015 ◽  
Vol 39 ◽  
pp. 61-66 ◽  
Author(s):  
Yang Shen ◽  
Liang Chen ◽  
Lingai Su ◽  
Yanyan Dong ◽  
Yunsheng Qian ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Oxygen Activation

scholarly journals The 3-His Metal Coordination Site Promotes the Coupling of Oxygen Activation to Cysteine Oxidation in Cysteine Dioxygenase

Biochemistry ◽  
2020 ◽  
Vol 59 (21) ◽  
pp. 2022-2031
Author(s):  
Dianna L. Forbes ◽  
Kathleen M. Meneely ◽  
Annemarie S. Chilton ◽  
Audrey L. Lamb ◽  
Holly R. Ellis
Keyword(s):  
Oxygen Activation ◽  
Metal Coordination ◽  
Cysteine Dioxygenase ◽  
Cysteine Oxidation ◽  
Coordination Site

scholarly journals Connecting the solubility and CCN activation of complex organic aerosols: a theoretical study using the Solubility Basis Set (SBS)

2014 ◽  
Vol 14 (21) ◽  
pp. 28523-28569 ◽  
Author(s):  
I. Riipinen ◽  
N. Rastak ◽  
S. N. Pandis
Keyword(s):  
Theoretical Study ◽  
Organic Aerosol ◽  
Water Soluble ◽  
Basis Set ◽  
Activation Process ◽  
Complete Dissolution ◽  
Organic Mixture ◽  
Solubility Range ◽  
Special Cases ◽  
Complex Organic

Abstract. We present a theoretical study investigating the cloud condensation nucleus (CCN) activation of multicomponent organic mixtures. We modeled these complex mixtures using the solubility basis set (SBS, analogous to the volatility basis set VBS), describing the mixture as a set of surrogate compounds with varying water-solubilities in a given range. We conducted Köhler theory calculations for 144 different mixtures with varying solubility range, number of components, assumption about the organic mixture thermodynamics and the shape of the solubility distribution, yielding approximately 6000 unique CCN-activation points. The results from these comprehensive calculations were compared to three simplifying assumptions about organic aerosol solubility: (1) complete dissolution at the point of activation, (2) combining the aerosol solubility with the molar mass and density into a single hygroscopicity parameter κ, (3) assuming a fixed water-soluble fraction ϵeff. While the complete dissolution was able to reproduce the activation points with a reasonable accuracy only when the majority (70–80%) of the material was dissolved at the point of activation, the single parameter representations of complex mixture solubility were confirmed to be powerful semi-empirical tools for representing the CCN activation of organic aerosol. Depending on the condensed-phase interactions between the organic molecules, material with solubilities larger than about 1–10 g L−1 could be treated as completely soluble in the CCN activation process over particle dry diameters between 20 and 500 nm and supersaturations between 0.03 and 8%. Our results indicate that understanding the details of the solubility distribution in the range of 0.1 to 100 g L−1 is critical for capturing the CCN activation, while resolution outside this solubility range will probably not add much information except in some special cases. The connection of these results to the previous observations of the CCN activation of complex organic mixture aerosols is discussed.

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