Chapter 1. Experimental and Computational Studies on the Catalytic Mechanism of Non-heme Iron Dioxygenases

2011 ◽  
pp. 1-41 ◽  
Author(s):  
Sam P. De Visser
Keyword(s):  
Catalytic Mechanism ◽  
Heme Iron ◽  
Computational Studies ◽  
Non Heme Iron

scholarly journals Structure and Reactivity of a High-Spin, Non-Heme Iron(III)-Superoxo Complex Supported by Phosphinimide Ligands

2021 ◽  
Author(s):  
Charles Winslow ◽  
Heui Beom Lee ◽  
Mackenzie J. Field ◽  
Simon J Teat ◽  
Jonathan Rittle
Keyword(s):  
Single Crystals ◽  
High Spin ◽  
Heme Iron ◽  
Computational Studies ◽  
Oxidation Processes ◽  
Transient Nature ◽  
Non Heme Iron ◽  
The Stability ◽  
Oxidation Chemistry ◽  
High Spin Iron

Non-heme iron oxygenases utilize dioxygen to accomplish challenging chemical oxidations. Further understanding of the Fe-O<sub>2</sub> intermediates implicated in these processes is challenged by their highly transient nature. To that end, we have developed a ligand platform featuring phosphinimide donors intended to stabilize oxidized, high-spin iron complexes. O<sub>2</sub> exposure of single crystals of a three-coordinate Fe(II) complex of this framework allowed for in crystallo trapping of a terminally-bound Fe-O<sub>2</sub> complex suitable for XRD characterization. Spectroscopic and computational studies of this species support a high-spin Fe(III) center antiferromagnetically coupled to a superoxide ligand, similar to that proposed for numerous non-heme iron oxygenases. In addition to the stability of this synthetic Fe-O<sub>2</sub> complex, its ability to engage in a range of stoichiometric and catalytic oxidation processes demonstrates that this iron-phosphinimide system is primed for development in modelling oxidizing bioinorganic intermediates and green oxidation chemistry.

scholarly journals Structure and Reactivity of a High-Spin, Non-Heme Iron(III)-Superoxo Complex Supported by Phosphinimide Ligands

2021 ◽  
Author(s):  
Charles Winslow ◽  
Heui Beom Lee ◽  
Mackenzie J. Field ◽  
Simon J Teat ◽  
Jonathan Rittle
Keyword(s):  
Single Crystals ◽  
High Spin ◽  
Heme Iron ◽  
Computational Studies ◽  
Oxidation Processes ◽  
Transient Nature ◽  
Non Heme Iron ◽  
The Stability ◽  
Oxidation Chemistry ◽  
High Spin Iron

Non-heme iron oxygenases utilize dioxygen to accomplish challenging chemical oxidations. Further understanding of the Fe-O<sub>2</sub> intermediates implicated in these processes is challenged by their highly transient nature. To that end, we have developed a ligand platform featuring phosphinimide donors intended to stabilize oxidized, high-spin iron complexes. O<sub>2</sub> exposure of single crystals of a three-coordinate Fe(II) complex of this framework allowed for in crystallo trapping of a terminally-bound Fe-O<sub>2</sub> complex suitable for XRD characterization. Spectroscopic and computational studies of this species support a high-spin Fe(III) center antiferromagnetically coupled to a superoxide ligand, similar to that proposed for numerous non-heme iron oxygenases. In addition to the stability of this synthetic Fe-O<sub>2</sub> complex, its ability to engage in a range of stoichiometric and catalytic oxidation processes demonstrates that this iron-phosphinimide system is primed for development in modelling oxidizing bioinorganic intermediates and green oxidation chemistry.

Strongly Coupled Redox-Linked Conformational Switching at the Active Site of the Non-Heme Iron-Dependent Dioxygenase, TauD

2019 ◽  
Author(s):  
Christopher John ◽  
Greg M. Swain ◽  
Robert P. Hausinger ◽  
Denis A. Proshlyakov
Keyword(s):  
Active Site ◽  
Structural Model ◽  
Heme Iron ◽  
Chemical Transformations ◽  
Experimental Conditions ◽  
Strongly Coupled ◽  
Non Heme Iron ◽  
Reversible Redox ◽  
Wide Range ◽  
Complex Structural

2-Oxoglutarate (2OG)-dependent dioxygenases catalyze C-H activation while performing a wide range of chemical transformations. In contrast to their heme analogues, non-heme iron centers afford greater structural flexibility with important implications for their diverse catalytic mechanisms. We characterize an <i>in situ</i> structural model of the putative transient ferric intermediate of 2OG:taurine dioxygenase (TauD) by using a combination of spectroelectrochemical and semi-empirical computational methods, demonstrating that the Fe (III/II) transition involves a substantial, fully reversible, redox-linked conformational change at the active site. This rearrangement alters the apparent redox potential of the active site between -127 mV for reduction of the ferric state and 171 mV for oxidation of the ferrous state of the 2OG-Fe-TauD complex. Structural perturbations exhibit limited sensitivity to mediator concentrations and potential pulse duration. Similar changes were observed in the Fe-TauD and taurine-2OG-Fe-TauD complexes, thus attributing the reorganization to the protein moiety rather than the cosubstrates. Redox difference infrared spectra indicate a reorganization of the protein backbone in addition to the involvement of carboxylate and histidine ligands. Quantitative modeling of the transient redox response using two alternative reaction schemes across a variety of experimental conditions strongly supports the proposal for intrinsic protein reorganization as the origin of the experimental observations.

Plant carotenoid cleavage oxygenases: structure–function relationships and role in development and metabolism

2019 ◽  
Vol 19 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Manoj Kumar Dhar ◽  
Sonal Mishra ◽  
Archana Bhat ◽  
Sudha Chib ◽  
Sanjana Kaul
Keyword(s):  
Higher Plants ◽  
Domain Architecture ◽  
Heme Iron ◽  
Critical Assessment ◽  
Protein Family ◽  
Regulatory Mechanisms ◽  
Non Heme Iron ◽  
Functional Aspects ◽  
Functional Understanding ◽  
Signal Production

Abstract A plant communicates within itself and with the outside world by deploying an array of agents that include several attractants by virtue of their color and smell. In this category, the contribution of ‘carotenoids and apocarotenoids’ is very significant. Apocarotenoids, the carotenoid-derived compounds, show wide representation among organisms. Their biosynthesis occurs by oxidative cleavage of carotenoids, a high-value reaction, mediated by carotenoid cleavage oxygenases or carotenoid cleavage dioxygenases (CCDs)—a family of non-heme iron enzymes. Structurally, this protein family displays wide diversity but is limited in its distribution among plants. Functionally, this protein family has been recognized to offer a role in phytohormones, volatiles and signal production. Further, their wide presence and clade-specific functional disparity demands a comprehensive account. This review focuses on the critical assessment of CCDs of higher plants, describing recent progress in their functional aspects and regulatory mechanisms, domain architecture, classification and localization. The work also highlights the relevant discussion for further exploration of this multi-prospective protein family for the betterment of its functional understanding and improvement of crops.

scholarly journals Activation modes in biocatalytic radical cyclization reactions

2021 ◽  
Author(s):  
Yuxuan Ye ◽  
Haigen Fu ◽  
Todd K Hyster
Keyword(s):  
Heme Iron ◽  
Radical Cyclization ◽  
Cytochrome P450 Monooxygenases ◽  
Radical Cyclizations ◽  
Cyclization Reactions ◽  
Complex Molecules ◽  
P450 Monooxygenases ◽  
Non Heme Iron ◽  
Essential Reactions ◽  
Isopenicillin N

Abstract Radical cyclizations are essential reactions in the biosynthesis of secondary metabolites and the chemical synthesis of societally valuable molecules. In this review, we highlight the general mechanisms utilized in biocatalytic radical cyclizations. We specifically highlight cytochrome P450 monooxygenases (P450s) involved in the biosynthesis of mycocyclosin and vancomycin, non-heme iron- and α-ketoglutarate-dependent dioxygenases (Fe/αKGDs) used in the biosynthesis of kainic acid, scopolamine, and isopenicillin N, and radical S-adenosylmethionine (SAM) enzymes that facilitate the biosynthesis of oxetanocin A, menaquinone, and F420. Beyond natural mechanisms, we also examine repurposed flavin-dependent ‘ene’-reductases (ERED) for non-natural radical cyclization. Overall, these general mechanisms underscore the opportunity for enzymes to augment and enhance the synthesis of complex molecules using radical mechanisms.

scholarly journals Non-heme Iron Proteins

1968 ◽  
Vol 243 (23) ◽  
pp. 6262-6272 ◽  
Author(s):  
J N Tsunoda ◽  
K T Yasunobu ◽  
H R Whiteley
Keyword(s):  
Heme Iron ◽  
Iron Proteins ◽  
Non Heme Iron
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