Cover Picture: Kinetic Studies on the Reaction between Cob(I)alamin and Peroxynitrite: Rapid Oxidation of Cob(I)alamin to Cob(II)alamin by Peroxynitrous Acid / Mechanistic Studies on the Reaction between Cob(II)alamin and Peroxynitrite: Evidence for a Dua

2011 ◽  
Vol 17 (42) ◽  
pp. 11673-11673 ◽  
Author(s):  
Riya Mukherjee ◽  
Nicola E. Brasch ◽  
Riya Mukherjee ◽  
Nicola E. Brasch
Keyword(s):  
Kinetic Studies ◽  
Peroxynitrous Acid ◽  
Mechanistic Studies

scholarly journals Aspartate or arginine? Validated redox state X-ray structures elucidate mechanistic subtleties of FeIV = O formation in bacterial dye-decolorizing peroxidases

2021 ◽  
Vol 26 (7) ◽  
pp. 743-761
Author(s):  
Marina Lučić ◽  
Michael T. Wilson ◽  
Dimitri A. Svistunenko ◽  
Robin L. Owen ◽  
Michael A. Hough ◽  
...  
Keyword(s):  
Redox State ◽  
Kinetic Studies ◽  
Site Directed Mutagenesis ◽  
X Rays ◽  
Mechanistic Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
Structural Framework ◽  
Solvent Isotope ◽  
Heme Peroxidases

AbstractStructure determination of proteins and enzymes by X-ray crystallography remains the most widely used approach to complement functional and mechanistic studies. Capturing the structures of intact redox states in metalloenzymes is critical for assigning the chemistry carried out by the metal in the catalytic cycle. Unfortunately, X-rays interact with protein crystals to generate solvated photoelectrons that can reduce redox active metals and hence change the coordination geometry and the coupled protein structure. Approaches to mitigate such site-specific radiation damage continue to be developed, but nevertheless application of such approaches to metalloenzymes in combination with mechanistic studies are often overlooked. In this review, we summarize our recent structural and kinetic studies on a set of three heme peroxidases found in the bacterium Streptomyces lividans that each belong to the dye decolourizing peroxidase (DyP) superfamily. Kinetically, each of these DyPs has a distinct reactivity with hydrogen peroxide. Through a combination of low dose synchrotron X-ray crystallography and zero dose serial femtosecond X-ray crystallography using an X-ray free electron laser (XFEL), high-resolution structures with unambiguous redox state assignment of the ferric and ferryl (FeIV = O) heme species have been obtained. Experiments using stopped-flow kinetics, solvent-isotope exchange and site-directed mutagenesis with this set of redox state validated DyP structures have provided the first comprehensive kinetic and structural framework for how DyPs can modulate their distal heme pocket Asp/Arg dyad to use either the Asp or the Arg to facilitate proton transfer and rate enhancement of peroxide heterolysis. Graphic abstract

Hierarchical silica monoliths with submicron macropores as continuous-flow microreactors for reaction kinetic and mechanistic studies in heterogeneous catalysis

2018 ◽  
Vol 3 (3) ◽  
pp. 353-364 ◽  
Author(s):  
Richard Kohns ◽  
Christian P. Haas ◽  
Alexandra Höltzel ◽  
Christian Splith ◽  
Dirk Enke ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Continuous Flow ◽  
Reaction Kinetic ◽  
Kinetic Studies ◽  
Mechanistic Studies ◽  
Silica Monoliths ◽  
Flow Microreactors

The proposed scheme enables academic laboratories to prepare hierarchical silica monoliths as continuous-flow microreactors for kinetic studies in heterogeneous catalysis.

Phosphine-catalyzed [3 + 2] annulation of 2-aminoacrylates with allenoates and mechanistic studies

2020 ◽  
Vol 10 (12) ◽  
pp. 3959-3964 ◽  
Author(s):  
Xiao-Yun Wu ◽  
Hou-Ze Gui ◽  
Harish Jangra ◽  
Yin Wei ◽  
Hendrik Zipse ◽  
...  
Keyword(s):  
Catalytic Mechanism ◽  
Kinetic Studies ◽  
Mechanistic Studies ◽  
Stereogenic Center

A phosphine catalyzed formal [3 + 2] annulation was disclosed, affording 3-pyrrolines containing an amino quaternary stereogenic center in good to excellent yields. The catalytic mechanism was investigated by DFT and kinetic studies.

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