scholarly journals Tracking Conformational Changes in Calmodulin in vitro, in Cell Extract, and in Cells by Electron Paramagnetic Resonance Distance Measurements

ChemPhysChem ◽  
2019 ◽  
Vol 20 (14) ◽  
pp. 1860-1868 ◽  
Author(s):  
Arina Dalaloyan ◽  
Andrea Martorana ◽  
Yoav Barak ◽  
Diana Gataulin ◽  
Eitan Reuveny ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Conformational Changes ◽  
Cell Extract ◽  
Distance Measurements ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic ◽  
In Cells

ДИНИТРОЗИЛЬНЫЕ КОМПЛЕКСЫ ЖЕЛЕЗА C ТИОЛСОДЕРЖАЩИМИ ЛИГАНДАМИ ПРЕДСТАВЛЕНЫ В ЖИВЫХ ОРГАНИЗМАХ В ОСНОВНОМ ИХ БИЯДЕРНОЙ ФОРМОЙ

2020 ◽  
Vol 65 (6) ◽  
pp. 1142-1153
Author(s):  
В.Д. Микоян ◽  
◽  
Е.Н. Бургова ◽  
Р.Р. Бородулин ◽  
А.Ф. Ванин ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Sodium Nitrite ◽  
Iron Complexes ◽  
Paramagnetic Resonance ◽  
First Case ◽  
Dinitrosyl Iron ◽  
Electron Paramagnetic ◽  
Dinitrosyl Complexes

The number of mononitrosyl iron complexes with diethyldithiocarbamate, formed in the liver of mice in vivo and in vitro after intraperitoneal injection of binuclear dinitrosyl iron complexes with N-acetyl-L-cysteine or glutathione, S-nitrosoglutathione, sodium nitrite or the vasodilating drug Isoket® was assessed by electron paramagnetic resonance (EPR). The number of the said complexes, in contrast to the complexes, formed after nitrite or Isoket administration, the level of which sharply increased after treatment of liver preparations with a strong reducing agent - dithionite, did not change in the presence of dithionite. It was concluded that, in the first case, EPR-detectable mononitrosyl iron complexes with diethyldithiocarbamate in the absence and presence of dithionite appeared as a result of the reaction of NO formed from nitrite with Fe2+-dieth- yldithiocarbamate and Fe3+-diethyldithiocarbamate complexes, respectively. In the second case, mononitrosyl iron complexes with diethyldithiocarbamate appeared as a result of the transition of iron-mononitosyl fragments from ready-made iron-dinitrosyl groups of binuclear dinitrosyl complexes, which is three to four times higher than the content of the mononuclear form of these complexes in the tissue...

scholarly journals Concentration of Fe(3+)-Triapine in BEAS-2B Cells

2019 ◽  
Vol 20 (12) ◽  
pp. 3062 ◽  
Author(s):  
William E. Antholine ◽  
Charles R. Myers
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Tumor Cells ◽  
Iron Uptake ◽  
Antitumor Agent ◽  
Epr Spectrum ◽  
Paramagnetic Resonance ◽  
Epr Method ◽  
First Time ◽  
Electron Paramagnetic ◽  
In Cells

An electron paramagnetic resonance (EPR) method was used to determine the concentration of the antitumor agent Triapine in BEAS-2B cells when Triapine was bound to iron (Fe). Knowledge of the concentration of Fe-Triapine in tumor cells may be useful to adjust the administration of the drug or to adjust iron uptake in tumor cells. An EPR spectrum is obtained for Fe(3+)-Triapine, Fe(3+)(Tp)2+, in BEAS-2B cells after addition of Fe(3+)(Tp)2+. Detection of the low spin signal for Fe(3+)(Tp)2+ shows that the Fe(3+)(Tp)2+ complex is intact in these cells. It is proposed that Triapine acquires iron from transferrin in cells including tumor cells. Here, it is shown that iron from purified Fe-transferrin is transferred to Triapine after the addition of ascorbate. To our knowledge, this is the first time that the EPR method has been used to determine the concentration of an iron antitumor agent in cells.

scholarly journals [FeFe]-Hydrogenase Maturation: H-Cluster Assembly Intermediates Tracked by Electron Paramagnetic Resonance, Infrared, and X-Ray Absorption Spectroscopy

2020 ◽  
Author(s):  
Brigitta Németh ◽  
Moritz Senger ◽  
Holly J. Redman ◽  
Pierre Ceccaldi ◽  
Joan Broderick ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Absorption Spectroscopy ◽  
Cluster Assembly ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Hydrogenase Maturation ◽  
Catalytically Active ◽  
X Ray Absorption ◽  
Electron Paramagnetic

[FeFe]-hydrogenase enzymes employ a unique organometallic cofactor for efficient and reversible hydrogen conversion. This so-called H-cluster consists of a [4Fe-4S] cubane cysteine-linked to a diiron complex coordinated by carbon monoxide and cyanide ligands and an azadithiolate ligand (adt = NH(CH2S)2). [FeFe]-hydrogenase apo-protein binding only the [4Fe-4S] sub-complex can be fully activated in vitro by the addition of a synthetic diiron site precursor complex ([2Fe]adt,). Elucidation of the mechanism of cofactor assembly will aid in the design of improved hydrogen processing synthetic catalysts. We combined in situ electron paramagnetic resonance, Fourier-transform infrared, and X-ray absorption spectroscopy to characterize intermediates of H-cluster assembly as initiated by mixing of the apo-protein (HydA1) from the green alga Chlamydomonas reinhardtii with [2Fe]adt. The three methods consistently show rapid formation of a complete H-cluster in the oxidized, CO-inhibited state (Hox-CO) already within seconds after the mixing. Moreover, FTIR spectroscopy support a model in which Hox-CO formation is preceded by a short-lived Hred´-CO like intermediate. Accumulation of Hox-CO was followed by CO release resulting in the slower conversion to the catalytically active state (Hox) as well as formation of reduced states of the H-cluster.

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