Electron paramagnetic resonance studies of the high-spin molecule Cr10(OMe)20(O2CCMe3)10

2005 ◽  
Vol 86 (3) ◽  
pp. 032507 ◽  
Author(s):  
Sonia Sharmin ◽  
Arzhang Ardavan ◽  
Stephen J. Blundell ◽  
Amalia I. Coldea ◽  
Eric J. L. McInnes ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
High Spin ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

Mössbauer, Electron Paramagnetic Resonance, and Theoretical Study of a High-Spin, Four-Coordinate Fe(II) Diketiminate Complex

2008 ◽  
Vol 47 (19) ◽  
pp. 8687-8695 ◽  
Author(s):  
Sebastian A. Stoian ◽  
Jeremy M. Smith ◽  
Patrick L. Holland ◽  
Eckard Münck ◽  
Emile L. Bominaar
Keyword(s):  
Electron Paramagnetic Resonance ◽  
High Spin ◽  
Theoretical Study ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

scholarly journals Electron-paramagnetic-resonance studies of leghaemoglobins from soya-bean and cowpea root nodules. Identification of nitrosyl-leghaemoglobin in crude leghaemoglobin preparations

1977 ◽  
Vol 167 (2) ◽  
pp. 435-445 ◽  
Author(s):  
C. Sidney Maskall ◽  
John F. Gibson ◽  
Peter J. Dart
Keyword(s):  
Electron Paramagnetic Resonance ◽  
High Spin ◽  
Root Nodules ◽  
Deae Cellulose ◽  
Soya Bean ◽  
Paramagnetic Resonance ◽  
Imidazole Complexes ◽  
Electron Paramagnetic ◽  
Haem Iron ◽  
Nitrosyl Derivative

1. Leghaemoglobins from soya-bean (Glycine max) and cowpea (Vigna unguiculata) root nodules were purified by chromatography on DEAE-cellulose phosphate columns at pH8.0 and pH5.8, to avoid the relatively low pH (5.2) commonly used to purify these proteins. 2. E.p.r. (electron-paramagnetic-resonance) spectra of the fluoride, azide, hydroxide and cyanide complexes of these ferric leghaemoglobins were very similar to the spectra of the corresponding myoglobin derivatives, indicating that the immediate environment of the iron in leghaemoglobin and myoglobin is similar, an imidazole moiety of histidine being the proximal ligand to the haem iron [cf. Appleby, Blumberg, Peisach, Wittenberg & Wittenberg (1976) J. Biol. Chem.251, 6090–6096]. 3. E.p.r. spectra of the acid-metleghaemoglobins showed prominent high-spin features very near g=6 and g=2 and, unlike myoglobin, small low-spin absorptions near g=2.26, 2.72 and 3.14. The width of the g=6 absorption derivative at 10–20K was about 4–4.5mT, similar to the value for acid-methaemoglobin. In contrast, a recently published (Appleby et al., 1976) spectrum of acid-metleghaemoglobin a had less high-spin character and a much broader absorption derivative around g=6. 4. E.p.r. spectra of ferric leghaemoglobin nicotinate and imidazole complexes suggest that the low-spin absorption near g=3.14 can be attributed to a trace of ferric leghaemoglobin nicotinate, and those near g=2.26 and 2.72 are from an endogenous dihistidyl haemichrome. 5. A large e.p.r. signal at g=2 in all samples of crude leghaemoglobin was shown to be from nitrosyl-leghaemoglobin. A soya-bean sample contained 27±3% of the latter. A previously unidentified form of soya-bean ferrous leghaemoglobin a was shown to be its nitrosyl derivative. If this is not an artifact, and occurs in the root nodule, the nitrosyl radical may interfere with the function of leghaemoglobin.

scholarly journals EPR Study of Paramagnetic Centers in Human Blood

2013 ◽  
Vol 36 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Tomasz Kubiak ◽  
Ryszard Krzyminiewski ◽  
Bernadeta Dobosz
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Healthy Volunteers ◽  
High Spin ◽  
Human Blood ◽  
Iron Complex ◽  
Disease Entity ◽  
Paramagnetic Centers ◽  
Paramagnetic Resonance ◽  
X Band ◽  
Electron Paramagnetic

Abstract Electron paramagnetic resonance investigations of paramagnetic centers in whole human blood were carried out at 170 K using X-band EPR spectrometer. The study included a group of patients and healthy volunteers. The EPR signals from high spin Fe3+ ions in transferrin (g = 4.2) and Cu2+ ions in ceruloplasmin (g = 2.05) are characteristic of each frozen blood sample. An overview of all recorded spectra revealed in several cases additional lines derived from high spin Fe3+ ions in methemoglobin (g = 5.8 - 6), free radicals (g = 2.002 - 2.005) and various low spin ferriheme complexes (g = 2.21 - 2.91). The lines from cytochromes (g = 3.03 and 3.27) were observed only twice. The EPR measurements have not confirmed the correlation between the occurrence of a particular type of low-spin iron complex and a specific disease entity. Moreover, the presence of EPR lines from trivalent iron also did not differentiate patients from healthy volunteers.

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