Dioxygenation of cysteamine to hypotaurine at a tris(pyrazolyl)borate iron(<scp>ii</scp>) unit – cysteamine dioxygenase mimicking?

Sallmann, Madleen; Braun, Beatrice; Limberg, Christian

doi:10.1039/c5cc01083g

Cited by 24 publications

(32 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Lower concentrations of O 2 were obtained by injecting anaerobic solutions of the Fe(II) complex into O 2 -saturated solutions of CH 2 Cl 2 in varying amounts. Following established procedures, 36–37 the products of the oxygenation reactions were isolated by addition of 3 M HCl to the reaction mixture and stirred for 3 hours. The aqueous layer was collected and the solvent removed under vacuum.…”

Section: Experimental and Computational Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis, X-ray Structures, Electronic Properties, and O₂/NO Reactivities of Thiol Dioxygenase Active-Site Models

et al. 2016

View full text Add to dashboard Cite

Mononuclear nonheme iron complexes that serve as structural and functional mimics of the thiol dioxygenases (TDOs), cysteine dioxygenase (CDO) and cysteamine dioxygenase (ADO), have been prepared and characterized with crystallographic, spectroscopic, kinetic, and computational methods. The high-spin Fe(II) complexes feature the facially-coordinating tris(4,5-diphenyl-1-methylimidazol-2-yl)phosphine (Ph2TIP) ligand that replicates the three histidine (3His) triad of the TDO active sites. Further coordination with bidentate L-cysteine ethyl ester (CysOEt) or cysteamine (CysAm) anions yielded five-coordinate (5C) complexes that resemble the substrate-bound forms of CDO and ADO, respectively. Detailed electronic-structure descriptions of the [Fe(Ph2TIP)(LS,N)]BPh4 complexes, where LS,N = CysOEt (1) or CysAm (2), were generated through a combination of spectroscopic techniques [electronic absorption, magnetic circular dichroism (MCD)] and density functional theory (DFT). Complexes 1 and 2 decompose in the presence of O2 to yield the corresponding sulfinic acid (RSO2H) products, thereby emulating the reactivity of the TDO enzymes and related complexes. Rate constants and activation parameters for the dioxygenation reactions were measured and interpreted with the aid of DFT calculations for O2-bound intermediates. Treatment of the TDO models with nitric oxide (NO) – a well-established surrogate of O2 – led to a mixture of high-spin and low-spin {FeNO}7 species at low temperature (−70 °C), as indicated by electron paramagnetic resonance (EPR) spectroscopy. At room temperature, these Fe/NO adducts convert to a common species with EPR and infrared (IR) features typical of cationic dinitrosyl iron complexes (DNICs). To complement these results, parallel spectroscopic, computational, and O2/NO reactivity studies were carried out using previously-reported TDO models that feature an anionic hydrotris(3-phenyl-5-methyl-pyrazolyl)borate (Ph,MeTp−) ligand. Though the O2 reactivities of the Ph2TIP- and Ph,MeTp-based complexes are quite similar, the supporting ligand perturbs the energies of Fe 3d-based molecular orbitals and modulates Fe-S bond covalency, suggesting possible rationales for the presence of neutral 3His coordination in CDO and ADO.

show abstract

Section: Experimental and Computational Methodsmentioning

confidence: 99%

“… a Reference 36. b Reference 37. c Obtained from an X-ray structure of Cys-bound CDO (PDB 4JTO; 2.0 Å resolution). …”

Section: Figurementioning

confidence: 99%

Synthesis, X-ray Structures, Electronic Properties, and O₂/NO Reactivities of Thiol Dioxygenase Active-Site Models

et al. 2016

View full text Add to dashboard Cite

show abstract

“…In a subsequent report, a similar S -oxygenation reaction was observed with the related cysteamine complex [Tp Me,Ph Fe II -(SCH 2 CH 2 NH 2 )]. 144 It should be mentioned that there is also related work on a well-defined chromium(III)–superoxo complex, derived from Cr II and O 2 , that reacts with thioether substrates to give sulfoxide products. This system was discussed in the context of the proposed mechanism for CDO.…”

Section: Dioxygen Activation By Nonheme Iron Complexesmentioning

confidence: 99%

Activation of Dioxygen by Iron and Manganese Complexes: A Heme and Nonheme Perspective

2016

View full text Add to dashboard Cite

The rational design of well-defined, first-row transition metal complexes that can activate dioxygen has been a challenging goal for the synthetic inorganic chemist. The activation of O2 is important in part because of its central role in the functioning of metalloenzymes, which utilize O2 to perform a number of challenging reactions including the highly selective oxidation of various substrates. There is also great interest in utilizing O2, an abundant and environmentally benign oxidant, in synthetic catalytic oxidation systems. This Perspective brings together recent examples of biomimetic Fe and Mn complexes that can activate O2 in heme or nonheme-type ligand environments. The use of oxidants such as hypervalent iodine (e.g., ArIO), peracids (e.g., m-CPBA), peroxides (e.g., H2O2) or even superoxide is a popular choice for accessing well-characterized metal–superoxo, metal–peroxo, or metal–oxo species, but the instances of biomimetic Fe/Mn complexes that react with dioxygen to yield such observable metal–oxygen species are surprisingly few. This Perspective focuses on mononuclear Fe and Mn complexes that exhibit reactivity with O2 and lead to spectroscopically observable metal–oxygen species, and/or oxidize biologically relevant substrates. Analysis of these examples reveals that solvent, spin state, redox potential, external co-reductants, and ligand architecture can all play important roles in the O2 activation process.

show abstract

“…Scheme Our understanding of CDO catalysis has been advanced through the development of synthetic models that replicate key features of the enzyme active site. [41][42][43][44][45][46][47][48] In 2012, the Limberg group reported the fivecoordinate complex [Fe(Tp Ph,Me )(CysOEt)] (1), where Tp Ph,Me is hydrotris(3-phenyl-5methylpyrazolyl)borate and CysOEt is the anion of l-cysteine ethyl ester (Scheme 3). 46 More recently, our group employed the tris(4,5-diphenylimidazol-2-yl)phosphine chelate (2-TIP Ph2 ; Scheme 3) to generate the related CDO mimic [Fe(2-TIP Ph2 )(CysOEt)]BPh4 (2).…”

Section: Introductionmentioning

confidence: 99%

The impact of simulation sequencing on perceived clinical decision making

Woda

Hansen

Paquette

et al. 2017

Nurse Education in Practice

View full text Add to dashboard Cite

An emerging nursing education trend is to utilize simulated learning experiences as a means to optimize competency and decision making skills. The purpose of this study was to examine differences in students' perception of clinical decision making and clinical decision making-related self-confidence and anxiety based on the sequence (order) in which they participated in a block of simulated versus hospital-based learning experiences. A quasi-experimental crossover design was used. Between and within group differences were found relative to self-confidence with the decision making process. When comparing groups, at baseline the simulation followed by hospital group had significantly higher self-confidence scores, however, at 14-weeks both groups were not significantly different. Significant within group differences were found in the simulation followed by hospital group only, demonstrating a significant decrease in clinical decision making related anxiety across the semester. Finally, there were no significant difference in; perceived clinical decision making within or between the groups at the two measurement points. Preliminary findings suggest that simulated learning experiences can be offered with alternating sequences without impacting the process, anxiety or confidence with clinical decision making. This study provides beginning evidence to guide curriculum development and allow flexibility based on student needs and available resources.

show abstract

Dioxygenation of cysteamine to hypotaurine at a tris(pyrazolyl)borate iron(ii) unit – cysteamine dioxygenase mimicking?

Cited by 24 publications

References 11 publications

Synthesis, X-ray Structures, Electronic Properties, and O₂/NO Reactivities of Thiol Dioxygenase Active-Site Models

Synthesis, X-ray Structures, Electronic Properties, and O₂/NO Reactivities of Thiol Dioxygenase Active-Site Models

Activation of Dioxygen by Iron and Manganese Complexes: A Heme and Nonheme Perspective

The impact of simulation sequencing on perceived clinical decision making

Contact Info

Product

Resources

About

Dioxygenation of cysteamine to hypotaurine at a tris(pyrazolyl)borate iron(ii) unit – cysteamine dioxygenase mimicking?

Cited by 24 publications

References 11 publications

Synthesis, X-ray Structures, Electronic Properties, and O2/NO Reactivities of Thiol Dioxygenase Active-Site Models

Synthesis, X-ray Structures, Electronic Properties, and O2/NO Reactivities of Thiol Dioxygenase Active-Site Models

Activation of Dioxygen by Iron and Manganese Complexes: A Heme and Nonheme Perspective

The impact of simulation sequencing on perceived clinical decision making

Contact Info

Product

Resources

About

Synthesis, X-ray Structures, Electronic Properties, and O₂/NO Reactivities of Thiol Dioxygenase Active-Site Models

Synthesis, X-ray Structures, Electronic Properties, and O₂/NO Reactivities of Thiol Dioxygenase Active-Site Models