continuous oxidation
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2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Hui Tao ◽  
Takahiro Mori ◽  
Heping Chen ◽  
Shuang Lyu ◽  
Akihito Nonoyama ◽  
...  

AbstractNon-heme iron and α-ketoglutarate-dependent (Fe/αKG) oxygenases catalyze various oxidative biotransformations. Due to their catalytic flexibility and high efficiency, Fe/αKG oxygenases have attracted keen attention for their application as biocatalysts. Here, we report the biochemical and structural characterizations of the unusually promiscuous and catalytically versatile Fe/αKG oxygenase SptF, involved in the biosynthesis of fungal meroterpenoid emervaridones. The in vitro analysis revealed that SptF catalyzes several continuous oxidation reactions, including hydroxylation, desaturation, epoxidation, and skeletal rearrangement. SptF exhibits extremely broad substrate specificity toward various meroterpenoids, and efficiently produced unique cyclopropane-ring-fused 5/3/5/5/6/6 and 5/3/6/6/6 scaffolds from terretonins. Moreover, SptF also hydroxylates steroids, including androsterone, testosterone, and progesterone, with different regiospecificities. Crystallographic and structure-based mutagenesis studies of SptF revealed the molecular basis of the enzyme reactions, and suggested that the malleability of the loop region contributes to the remarkable substrate promiscuity. SptF exhibits great potential as a promising biocatalyst for oxidation reactions.


Author(s):  
Mingyu Gao ◽  
Pengfei Yang ◽  
Xinyi Zhang ◽  
Yani Zhang ◽  
Dianqing Li ◽  
...  

2021 ◽  
Author(s):  
Hui Tao ◽  
Takahiro Mori ◽  
Heping Chen ◽  
Shuang Lyu ◽  
Akihito Nonoyama ◽  
...  

Abstract Non-heme iron and α-ketoglutarate-dependent (Fe/αKG) oxygenases catalyze various oxidative biotransformations. Due to their catalytic flexibility and high efficiency, Fe/αKG oxygenases have attracted keen attention for their application as biocatalysts. Here, we report the biochemical and structural characterizations of the unusually promiscuous and catalytically versatile Fe/αKG oxygenase SptF, involved in the biosynthesis of fungal meroterpenoid emervaridones. The in vitro analysis reveals that SptF catalyzes four continuous oxidation reactions, including hydroxylation, desaturation, epoxidation, and skeletal rearrangement. SptF exhibits extremely broad substrate specificity toward various meroterpenoids, and efficiently produced novel cyclopropane-ring-fused 5/3/5/5/6/6 and 5/3/6/6/6 scaffolds from terretonins. Moreover, SptF also hydroxylates steroids, including androsterone, testosterone, and progesterone, with different regiospecificities. Crystallographic and structure-based mutagenesis studies of SptF reveal the molecular basis of the enzyme reactions, and suggest that the malleability of the loop region contributes to the remarkable substrate promiscuity. SptF exhibits great potential as a promising biocatalyst for oxidation reactions.


Author(s):  
Xinyi Zhang ◽  
Mingyu Gao ◽  
Pengfei Yang ◽  
Xiaochen Cui ◽  
Yanan Liu ◽  
...  

2021 ◽  
Author(s):  
Rosa V. Espinoza ◽  
Kersti Caddell Haatveit ◽  
S. Wald Grossman ◽  
Jin Yi Tan ◽  
Caylie A. McGlade ◽  
...  

<div> <div> <div> <p>Iterative P450 enzymes are powerful biocatalysts for selective late-stage C-H oxidation of complex natural product scaffolds. These enzymes represent new tools for selectivity and cascade reactions, facilitating direct access to core structure diversification. Recently, we reported the structure of the multifunctional bacterial P450 TamI and elucidated the molecular basis of its substrate binding and strict reaction sequence at distinct carbon atoms of the substrate. Here, we report the design and characterization of a toolbox of TamI biocatalysts, generated by mutations at Leu101, Leu244 and/or Leu295, that alter the native selectivity, step sequence and number of reactions catalyzed, including the engineering of a variant capable of catalyzing a four-step oxidative cascade without the assistance of the flavoprotein and oxidative partner TamL. The tuned enzymes override inherent substrate reactivity enabling catalyst- controlled C-H functionalization and alkene epoxidation of the tetramic acid-containing natural product tirandamycin. Five new, bioactive tirandamycin derivatives (6-10) were generated through TamI-mediated enzymatic synthesis. Quantum mechanics calculations and MD simulations provide important insights on the basis of altered selectivity and underlying biocatalytic mechanisms for enhanced continuous oxidation of the iterative P450 TamI. </p> </div> </div> </div>


2021 ◽  
Author(s):  
Rosa V. Espinoza ◽  
Kersti Caddell Haatveit ◽  
S. Wald Grossman ◽  
Jin Yi Tan ◽  
Caylie A. McGlade ◽  
...  

<div> <div> <div> <p>Iterative P450 enzymes are powerful biocatalysts for selective late-stage C-H oxidation of complex natural product scaffolds. These enzymes represent new tools for selectivity and cascade reactions, facilitating direct access to core structure diversification. Recently, we reported the structure of the multifunctional bacterial P450 TamI and elucidated the molecular basis of its substrate binding and strict reaction sequence at distinct carbon atoms of the substrate. Here, we report the design and characterization of a toolbox of TamI biocatalysts, generated by mutations at Leu101, Leu244 and/or Leu295, that alter the native selectivity, step sequence and number of reactions catalyzed, including the engineering of a variant capable of catalyzing a four-step oxidative cascade without the assistance of the flavoprotein and oxidative partner TamL. The tuned enzymes override inherent substrate reactivity enabling catalyst- controlled C-H functionalization and alkene epoxidation of the tetramic acid-containing natural product tirandamycin. Five new, bioactive tirandamycin derivatives (6-10) were generated through TamI-mediated enzymatic synthesis. Quantum mechanics calculations and MD simulations provide important insights on the basis of altered selectivity and underlying biocatalytic mechanisms for enhanced continuous oxidation of the iterative P450 TamI. </p> </div> </div> </div>


Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3974
Author(s):  
Thu ◽  
Besson

The production of brandy from wine and bioethanol from sugarcane in distilleries generates vinasses, which are effluents that are rich in organic matter. Since they have a high pollution load characterized by high chemical and biological oxygen demands and a dark color, the depollution of these effluents is inevitable. Pt and Ru catalysts supported on titania and zirconia were explored in the catalytic wet air oxidation (CWAO) processing of cognac and sugarcane wastewaters, in batch mode and in a trickle-bed reactor, at a temperature condition of 190 °C and a pressure condition of 70 bar air. The addition of a catalyst promoted total organic carbon (TOC) abatement and the oxidation of ammonium ions formed from organic nitrogen in the effluents to dinitrogen or nitrates. The best results in terms of selectivity to N2 were obtained by using Pt catalysts; a selectivity of 92% to N2 and a TOC removal of 90% were observed in continuous oxidation of the sugarcane vinasse.


2019 ◽  
Vol 36 (9) ◽  
pp. 1170-1178
Author(s):  
Rui Yin ◽  
Yuanjian Wang ◽  
Jia Zhang ◽  
Jizhi Zhou ◽  
Qiang Liu ◽  
...  

Fuel ◽  
2019 ◽  
Vol 248 ◽  
pp. 254-257 ◽  
Author(s):  
Jianbing Gao ◽  
Haibo Chen ◽  
Junyan Chen ◽  
Chaochen Ma ◽  
Guohong Tian ◽  
...  

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 450 ◽  
Author(s):  
Yu Zhang ◽  
Yongzhe Fan ◽  
Xue Zhao ◽  
An Du ◽  
Ruina Ma ◽  
...  

The influence of graphite morphology on the phase, microstructure and properties of hot dipping and diffusion aluminizing (HDDA) coating on flake/spheroidal graphite cast iron (FC/FCD) was investigated. The microstructure and properties of the HDDA coatings on FC/FCD were determined by the graphite morphology. The outer and inner layers of the HDDA coating comprised the Fe2Al5 and FeAl phases, respectively. The outer layer of HDDA on FCD was dense and uniform; however, some pores of different sizes were found in the outer coating on FC, resulting in looser HDDA coating. Hence, the wear resistance of the HDDA coating on FC was worse than that of the coating on FCD. During oxidation, many continuous oxidation channels were formed from the coating surface to the matrix in the HDDA coating on FC, resulting in the oxidation of graphite in the HDDA coating and the matrix. However, only exposed spheroidal graphite was oxidized in the HDDA coating on FCD. Thus, the high-temperature oxidation resistance of the HDDA coating on FC was also worse than that of the coating on FCD.


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