Home About us Contact
|
Home About us Contact | ||
|
|
||
Ferric Ions (ferric + ion)
Selected AbstractsThe antioxidant activity and stability of the phenolic fraction of green olives and extra virgin olive oilJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2001Turkan Keceli Abstract The antioxidant activity of phenolic extracts from olives and olive oil has been assessed by scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and by studying the effects on the stability of stripped olive oil in the absence and presence of ferric chloride. The olive extracts contained a much higher concentration (1940,5800,mg,kg,1) of phenolic components than the olive oil extract (180,mg,kg,1). Some olive extracts were more effective than the olive oil extract in scavenging DPPH radicals, but the three varieties of olives examined showed relatively large differences in both polyphenol concentration and antioxidant activity of extracts. ,-Tocopherol and extracts from both olives and olive oil were effective antioxidants in stripped olive oil at 60,°C. Ferric chloride reduced the stability of stripped olive oil, but the olive extract studied was significantly more effective as an antioxidant in the presence of the metal salt than the olive oil extract or ,-tocopherol. Ferric ions catalysed the oxidation of caffeic acid, oleuropein and phenolic components of the olive and olive oil extracts in aqueous solution (pH 5.4). The olive extract oxidised more rapidly than the olive oil extract in aqueous solution. © 2001 Society of Chemical Industry [source] Stabilization of High-Valent FeIVS6 -Cores by Dithiocarbamate(1,) and 1,2-Dithiolate(2,) Ligands in Octahedral [FeIV(Et2dtc)3,n(mnt)n](n,1), Complexes (n=0, 1, 2, 3): A Spectroscopic and Density Functional Theory Computational Study,CHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2010Carsten Milsmann Dr. Abstract A detailed spectroscopic and quantum chemical analysis is presented to elucidate the electronic structures of the octahedral complexes [Fe(Et2dtc)3,n(mnt)n]n, (1,4, n=3, 2, 1, 0) and their one-electron oxidized analogues [Fe(Et2dtc)3,n(mnt)n](n,1), (1ox,4ox); (mnt)2, represents maleonitriledithiolate(2,) and (Et2dtc)1, is the diethyldithiocarbamato(1,) ligand. By using X-ray crystallography, Mössbauer spectroscopy, and Fe and S K-edge X-ray absorption spectroscopy (XAS) it is convincingly shown that, in contrast to our previous studies on [Fe(cyclam)(mnt)]1+ (cyclam=1,4,8,11-tetraazacyclotetradecane), the oxidation of 1,4 is metal-centered yielding the genuine FeIV complexes 1ox,4ox. For the latter complexes, a spin ground state of S=1 has been established by magnetic susceptibility measurements, which indicates a low-spin d4 configuration. DFT calculations at the B3LYP level support this electronic structure and exclude the presence of a ligand , radical coordinated to an intermediate-spin ferric ion. Mössbauer parameters and XAS spectra have been calculated to calibrate our computational results against the experiment. Finally, a simple ligand-field approach is presented to correlate the structural features obtained from X-ray crystallography (100,K) with the spectroscopic data. [source] Definition of the residues required for the interaction between glycine-extended gastrin and transferrin in vitroFEBS JOURNAL, Issue 17 2009Suzana Kovac Transferrin is the main iron transport protein found in the circulation, and the level of transferrin saturation in the blood is an important indicator of iron status. The peptides amidated gastrin(17) (Gamide) and glycine-extended gastrin(17) (Ggly) are well known for their roles in controlling acid secretion and as growth factors in the gastrointestinal tract. Several lines of evidence, including the facts that transferrin binds gastrin, that gastrins bind ferric ions, and that the level of expression of gastrins positively correlates with transferrin saturation, suggest the possible involvement of the transferrin,gastrin interaction in iron homeostasis. In the present work, the interaction between gastrins and transferrin has been characterized by surface plasmon resonance and covalent crosslinking. First, an interaction between iron-free apo-transferrin and Gamide or Ggly was observed. The fact that no interaction was observed in the presence of the chelator EDTA suggested that the gastrin,ferric ion complex was the interacting species. Moreover, removal of ferric ions with EDTA reduced the stability of the complex between apo-transferrin and gastrins, and no interaction was observed between Gamide or Ggly and diferric transferrin. Second, some or all of glutamates at positions 8,10 of the Ggly molecule, together with the C-terminal domain, were necessary for the interaction with apo-transferrin. Third, monoferric transferrin mutants incapable of binding iron in either the N-terminal or C-terminal lobe still bound Ggly. These findings are consistent with the hypothesis that gastrin peptides bind to nonligand residues within the open cleft in each lobe of transferrin and are involved in iron loading of transferrin in vivo. Structured digital abstract ,,MINT-7212832, MINT-7212849: Apo-transferrin (uniprotkb:P02787) and Gamide (uniprotkb:P01350) bind (MI:0407) by surface plasmon resonance (MI:0107) ,,MINT-7212881, MINT-7212909: Ggly (uniprotkb:P01350) and Apo-transferrin (uniprotkb:P02787) bind (MI:0407) by cross-linking studies (MI:0030) ,,MINT-7212864: Apo-transferrin (uniprotkb:P02787) and Ggly (uniprotkb:P01350) bind (MI:0407) by competition binding (MI:0405) [source] | ||||||||||