Mossbauer spectroscopic studies

Caldeira J, R Eeicht, H White, M Teixeira, JJG Mourat, H Simon, 1 Moura (1996) EPR and Mossbauer spectroscopic studies on enoate reductase. J Biol Chem 271 18743-18748. 

The results of the XRD measurement showed that the Fe jAl, jPO catalyst was almost in amorphous state. Only a very broad peak at 29 of ca. 23 degree was observed. The Mossbauer spectroscopic study on this catalyst showed one doublet of iron with the isomeric shift of 0.31 mm s (a-Fe was used as the reference) and the quadrupole splitting of 0.62 mm s. These parameters are very close to those observed for FePO [13, 14], suggesting that the iron cation in the catalyst is tetrahedrally coordinated with oxygen and isolated by four PO tetrahedral units. Such coordination circumstance was suggested to be a key factor for the iron site effective for the oxidation of CH to CHjOH by H -Oj gas mixture [15]. 

Russo, U., Long, G.J. Mossbauer spectroscopic studies of the high oxidation states of iron. In Long, G.J., Grandjean, F. (eds.) Mossbauer Spectroscopy Applied to Inorganic Chemistry, pp. 289-329. Plenum, New York (1989)... 

Giitlich (1979) Mossbauer spectroscopic studies of spin crossover compounds [212]. 

Spectroscopic techniques may provide the least ambiguous methods for verification of actual sorption mechanisms. Zeltner et al. (Chapter 8) have applied FTIR (Fourier Transform Infrared) spectroscopy and microcalorimetric titrations in a study of the adsorption of salicylic acid by goethite these techniques provide new information on the structure of organic acid complexes formed at the goethite-water interface. Ambe et al. (Chapter 19) present the results of an emission Mossbauer spectroscopic study of sorbed Co(II) and Sb(V). Although Mossbauer spectroscopy can only be used for a few chemical elements, the technique provides detailed information about the molecular bonding of sorbed species and may be used to differentiate between adsorption and surface precipitation. 

Music, S. Vertes, A. Simmons, G.W Czako-Nagy, I. Leidheiser, H.Jr. (1982) Mossbauer spectroscopic study of the formation of Fe(III) oxyhydroxides and oxides by hydrolysis of aqueous Fe(III) salt solutions. J. Colloid Interface Sd. 85 256—266... 

St. Pierre,T.G. Bell, S.H. Dickson, D.P.E. Mann, S. Webb, J. Moore, G.R. Williams, R.J.P. (1986) Mossbauer spectroscopic studies of the cores of human, limpet and bacterial ferritins. Biochim. Biophys. Acta 870 127-134... 

Mossbauer spectroscopic study of reactions within rust layers. Corrosion Sd. 29 1329—... 

FABMS, 39 340-342 isolobal analogies, 39 378-381 ligand addition, elimination, and substitution reactions, 39 337-338 Mossbauer spectroscopic studies, 39 342-344... 

The first Mossbauer spectroscopic studies on this class of iron-sulfur proteins were carried out by Blomstrom et al. 174) who reported only spectra taken on the oxidized form of the protein from Clostridium pasteuranium. Evidence in the form of two partially resolved quadrupole pairs was presented to support two distinct environments for the iron in the oxidized form of the protein, the ratio of 5 2 was suggested in keeping with the then thought number of Fe atoms per protein molecule. This assignment of the number of Fe atom per site, of course, rests on the assumption of equal Lamb-Mossbauer recoil-free fractions for the two sites. 

Knudsen, J.E. Mossbauer spectroscopic studies of ferric hexaquo complex in amorphous frozen solutions at weak applied magnetic fields. J. Phys. Chem. Solids 1980, 41(6), 545-550. 

K. The stable antiferromagnetic ground state was also evident from the negative Weiss constant of —14 K and the monotonically increasing magnetization curve with a value of 2.8 p.b/Eu at 2 K and 5.5 T.151 Eu Mossbauer spectroscopic studies confirmed the divalent nature of europium in EuAuPb with an isomer shift value of —10.9 mm/s at 78 K. Line broadening in the Mossbauer spectra occurred around... 

Shaman, D. M. Vergo, N. (1988b) Optical (diffuse reflectance) and Mossbauer spectroscopic study of nontronite and related iron smectites. Amer. Mineral., 73, 1346—54. 

Combined EPR and 57Fe Mossbauer spectroscopic studies of the MoFe protein in various overall oxidation states39 40,42,44 48,49) have provided strong evidence for the presence of six metal clusters two M centers that are the protein-bound form of the FeMo-cofactor (a novel Mo-Fe-S cluster) and four unusual tetranuclear iron clusters referred to as the P clusters. These will be discussed separately below. In addition, Mossbauer spectra of MoFe proteins from Azotobacter vinelandii, Clostridium pas-teurianum, and Klebsiella pneumoniae all show an additional component termed S39 40 42, which accounts for 6% of the total Fe present (2 Fe per molecule) and which has Mossbauer parameters (AEq = 1.35 mm/s d = 0.60 mm/s) different from those expected for likely impurities such as high-spin Fe2+ or Fe3+ ( adventitious iron). At present, it is difficult to decide whether species S is an unusual and persistent impurity or an integral part of the MoFe protein. 

Figure 5 The heterodinuclear Mn" Fe " cluster of Chlamydia trachomatis RNR R2 protein and its proposed formation mechanism from its Mn"Fe" form described in a recent combined biochemical, EPR, and Mossbauer spectroscopic study (33-36).

Wolska, E., Subert, J, Haba, Z., Tlaskal, J. and Schwertmann, U. (1994) X.ray powder diffraction and Mossbauer spectroscopic studies on the solubility limits in a-FeOOH/a-AlOOH solid solutions. J. Mat. Sci. 29 3269-3273... 

Bell SH, Weir MP, Dickson DP, Gibson JF, Sharp GA, Peters TJ. Mossbauer spectroscopic studies of human haemosiderin and ferritin. Biochim Biophys Acta 1984 787 227-36. 

In line with these observations, earlier " Sn Mossbauer spectroscopic studies of rigid PVC samples containing Sn02 as a fire-retardant additive have shown that Sn(IV) is partially reduced to Sn(II) species (SnCl2 and SnO) and even to metallic tin during thermal degradation and combustion processes.In this case, the relatively involatile SnCb is detected in the char residue, whereas highly volatile SnCU is not. 

Goodman, B. A. and Cheshire, M. V. (1972). A Mossbauer spectroscopic study of the effect of pH on the reaction between iron and humic acid in aqueous media. J. Soil Sci. 30, 85-91. 

Since 1980, newer physical techniques such as Mdssbauer spectroscopy, X-ray absorption spectroscopy and iron-sulfur-core extrusion have been used to address the question of the structure of FeS-X. The initial Mossbauer spectroscopic study by (EH) Evans, Rush, Johnson and (MC W) Evans2o indicated... 

In the meantime, Scheller, Svendsen and Mpller carried out a careful analysis ofthe stoichiometry of polypeptide subunits relative to the primary donor P700 in the P700-chlorophyll a-protein isolated from barley. They found one mole of each ofthe two homologous subunits per mole ofP700, each with molecular masses of 82 kDa, as well as some lower-molecular-mass polypeptides. These results plus the accumulated information on the total number of iron and sulfur atoms relative to P700, and results of the renewed X-ray absorption and Mossbauer spectroscopic studies, have now conclusively confirmed the presence of a single [4Fe 4S] cluster in FeS-X in the PS-I reaction-center core. 

Mijssbauer Spectroscopy. Mossbauer spectroscopic studies of the polymers are reported here, and these provide the evidence to substantiate the structural differences between the polymers. 

---