Identification of an Intermediate Species along the Nitrile Hydratase Reaction Pathway by EPR Spectroscopy

Biochemistry ◽  
2021 ◽  
Author(s):  
Wasantha Lankathilaka Karunagala Pathiranage ◽  
Natalie Gumataotao ◽  
Adam T. Fiedler ◽  
Richard C. Holz ◽  
Brian Bennett
Keyword(s):  
Epr Spectroscopy ◽  
Nitrile Hydratase ◽  
Reaction Pathway ◽  
Intermediate Species

Cellular maturation of an iron-type nitrile hydratase interrogated using EPR spectroscopy

2019 ◽  
Vol 24 (7) ◽  
pp. 1105-1113
Author(s):  
K. P. Wasantha Lankathilaka ◽  
Natalia Stein ◽  
Richard C. Holz ◽  
Brian Bennett
Keyword(s):  
Epr Spectroscopy ◽  
Nitrile Hydratase

Switching a nitrilase from Syechocystis sp. PCC6803 to a nitrile hydratase by rationally regulating reaction pathways

2017 ◽  
Vol 7 (5) ◽  
pp. 1122-1128 ◽  
Author(s):  
Shuiqin Jiang ◽  
Lujia Zhang ◽  
Zhiqiang Yao ◽  
Bei Gao ◽  
Hualei Wang ◽  
...  
Keyword(s):  
Nitrile Hydratase ◽  
Reaction Pathway ◽  
Reaction Pathways

Based on this mechanism, a nitrilase was engineered to shift the reaction pathway from formation of acid to formation of amide.

scholarly journals An EPR characterisation of stable and transient reactive oxygen species formed under radiative and non-radiative conditions

2019 ◽  
Vol 45 (12) ◽  
pp. 5763-5779 ◽  
Author(s):  
E. Richards ◽  
D. M. Murphy ◽  
M. Che
Keyword(s):  
Reactive Oxygen Species ◽  
Epr Spectroscopy ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Intermediate Species ◽  
Paramagnetic Resonance ◽  
General Terms ◽  
Electron Paramagnetic ◽  
Ideal Method ◽  
The Ideal

Abstract Electron paramagnetic resonance (EPR) spectroscopy is the ideal method of choice when detecting and studying the wide variety of paramagnetic oxygen-centred radicals. For simple diatomic radicals, such as the superoxide (O2−) or peroxy $$ ({\text{ROO}}^{\bullet})$$(ROO∙) species, the CW EPR profile (in particular the g-values) of these species can appear similar and indeed indistinguishable in some cases. Experiments using 17O-enriched oxygen, revealing a rich 17O hyperfine pattern, are therefore essential to distinguish between the two species. However, in many cases, particularly involving TiO2 photocatalysis, the peroxy-type $$ ({\text{ROO}}^{\bullet})$$(ROO∙) radicals or other intermediate species such as the [O2−…organic]-type adducts can be transient in nature and once again can produce similar g-values. In general terms, these reactive oxygen species (ROS) are formed and detected at low-temperature conditions. Hence, the application of EPR spectroscopy to studies of surface-stabilised oxygen-centred radicals must be performed under carefully selected conditions in order to confidently distinguish between the differing types of diatomic radicals, such as O2−, $$ {\text{ROO}}^{\bullet}$$ROO∙ or [O2−…organic].

Electrochemical intermediate species and reaction pathway in H2 oxidation on solid electrolytes

2012 ◽  
Vol 48 (67) ◽  
pp. 8338 ◽  
Author(s):  
Farid El Gabaly ◽  
Anthony H. McDaniel ◽  
Michael Grass ◽  
William C. Chueh ◽  
Hendrik Bluhm ◽  
...  
Keyword(s):  
Solid Electrolytes ◽  
Reaction Pathway ◽  
Intermediate Species ◽  
H2 Oxidation

scholarly journals Production of 5-Hydroxymethylfurfural from Glucose in Water by Using Transition Metal-Oxide Nanosheet Aggregates

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 818 ◽  
Author(s):  
Atsushi Takagaki
Keyword(s):  
Catalytic Activity ◽  
Ion Exchange ◽  
Transition Metal ◽  
Metal Oxide ◽  
Metal Oxides ◽  
Kinetic Analysis ◽  
Reaction Pathway ◽  
Ion Exchange Resins ◽  
Intermediate Species ◽  
Exchange Resins

Metal-oxide nanosheet aggregates were prepared by exfoliation and subsequent aggregation of layered metal oxides and used for the conversion of glucose to 5-hydroxymethylfurfural (HMF) in water. Three aggregated nanosheets, HNbWO6, HNb3O8, and HTiNbO5, yielded HMF in water at 393–413 K, whereas ion-exchange resins and H-form zeolites did not. The catalytic activity of the nanosheets decreased in the order HNbWO6 > HNb3O8 > HTiNbO5, which correlates with their acidity. The HNbWO6 nanosheets exhibited higher selectivity for HMF than niobic acid, and the selectivity was improved in the water–toluene biphasic system. The selectivity for HMF over HNbWO6 nanosheets was higher from glucose than from fructose. Kinetic analysis suggested that in addition to fructose, an intermediate species was involved in the reaction pathway of HMF production from glucose.

scholarly journals Reaction Pathway toward Seven-Atom-Wide Armchair Graphene Nanoribbon Formation and Identification of Intermediate Species on Au(111)

2020 ◽  
Vol 124 (29) ◽  
pp. 16009-16018
Author(s):  
Sebastian Thussing ◽  
Sebastian Flade ◽  
Kristjan Eimre ◽  
Carlo A. Pignedoli ◽  
Roman Fasel ◽  
...  
Keyword(s):  
Reaction Pathway ◽  
Graphene Nanoribbon ◽  
Intermediate Species ◽  
Armchair Graphene Nanoribbon ◽  
Armchair Graphene

NMR and EPR Spectroscopy

1963 ◽  
Vol 36 (3_4) ◽  
pp. 247-248
Author(s):  
H. Dreeskamp
Keyword(s):  
Epr Spectroscopy

Catalytic Resonance Theory: Parallel Reaction Pathway Control

2019 ◽  
Author(s):  
M. Alexander Ardagh ◽  
Manish Shetty ◽  
Anatoliy Kuznetsov ◽  
Qi Zhang ◽  
Phillip Christopher ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Active Site ◽  
Active Sites ◽  
Reaction Pathway ◽  
Control Strategies ◽  
Oscillation Amplitude ◽  
Catalytic Performance ◽  
Parallel Reaction ◽  
Resonance Theory ◽  
Static Conditions

Catalytic enhancement of chemical reactions via heterogeneous materials occurs through stabilization of transition states at designed active sites, but dramatically greater rate acceleration on that same active site is achieved when the surface intermediates oscillate in binding energy. The applied oscillation amplitude and frequency can accelerate reactions orders of magnitude above the catalytic rates of static systems, provided the active site dynamics are tuned to the natural frequencies of the surface chemistry. In this work, differences in the characteristics of parallel reactions are exploited via selective application of active site dynamics (0 < ΔU < 1.0 eV amplitude, 10<sup>-6</sup> < f < 10<sup>4</sup> Hz frequency) to control the extent of competing reactions occurring on the shared catalytic surface. Simulation of multiple parallel reaction systems with broad range of variation in chemical parameters revealed that parallel chemistries are highly tunable in selectivity between either pure product, even when specific products are not selectively produced under static conditions. Two mechanisms leading to dynamic selectivity control were identified: (i) surface thermodynamic control of one product species under strong binding conditions, or (ii) catalytic resonance of the kinetics of one reaction over the other. These dynamic parallel pathway control strategies applied to a host of chemical conditions indicate significant potential for improving the catalytic performance of many important industrial chemical reactions beyond their existing static performance.

A Paramedic Treatment for Modeling Explicitly Solvated Chemical Reaction Mechanisms

2018 ◽  
Author(s):  
Yasemin Basdogan ◽  
John Keith
Keyword(s):  
Reaction Mechanism ◽  
Chemical Reaction ◽  
Reaction Mechanisms ◽  
Reaction Pathway ◽  
Optimization Procedure ◽  
Cost Effective ◽  
Chemical Reaction Mechanisms ◽  
Solvent Molecules ◽  
Dynamics Simulations ◽  
Mbh Reaction

<div> <div> <div> <p>We report a static quantum chemistry modeling treatment to study how solvent molecules affect chemical reaction mechanisms without dynamics simulations. This modeling scheme uses a global optimization procedure to identify low energy intermediate states with different numbers of explicit solvent molecules and then the growing string method to locate sequential transition states along a reaction pathway. Testing this approach on the acid-catalyzed Morita-Baylis-Hillman (MBH) reaction in methanol, we found a reaction mechanism that is consistent with both recent experiments and computationally intensive dynamics simulations with explicit solvation. In doing so, we explain unphysical pitfalls that obfuscate computational modeling that uses microsolvated reaction intermediates. This new paramedic approach can promisingly capture essential physical chemistry of the complicated and multistep MBH reaction mechanism, and the energy profiles found with this model appear reasonably insensitive to the level of theory used for energy calculations. Thus, it should be a useful and computationally cost-effective approach for modeling solvent mediated reaction mechanisms when dynamics simulations are not possible. </p> </div> </div> </div>

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