scholarly journals Iron K-edge X-ray absorption spectroscopy of the iron-molybdenum cofactor of nitrogenase from Klebsiella pneumoniae

1988 ◽  
Vol 252 (2) ◽  
pp. 421-425 ◽  
Author(s):  
J M Arber ◽  
A C Flood ◽  
C D Garner ◽  
C A Gormal ◽  
S S Hasnain ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Long Range ◽  
Absorption Spectroscopy ◽  
Molybdenum Cofactor ◽  
Published Data ◽  
Absorption Data ◽  
X Ray ◽  
Chemical Models ◽  
Iron Molybdenum Cofactor ◽  
X Ray Absorption

Iron K-edge X-ray absorption data for the iron-molybdenum cofactor (‘FeMoco’) from Klebsiella pneumoniae reported here provide the first evidence for long-range structural order in the cofactor [Fe…Fe(Mo) = 0.368 nm in addition to Fe…S = 0.22 nm and Fe…Fe(Mo) = 0.27 nm] and, in contrast with previously published data [Antonio, Teo, Orme-Johnson, Nelson, Groh, Lindahl, Kauzlarich & Averill (1982) J. Am. Chem. Soc. 104, 4703-4705], indicate that most of the iron centres are not co-ordinated to light (oxygen, nitrogen) atoms. This demonstrates that presently available chemical models for FeMoco are inadequate.

scholarly journals Comparison of Iron-Molybdenum Cofactor-deficient Nitrogenase MoFe Proteins by X-ray Absorption Spectroscopy

2004 ◽  
Vol 279 (27) ◽  
pp. 28276-28282 ◽  
Author(s):  
Mary C. Corbett ◽  
Yilin Hu ◽  
Farzad Naderi ◽  
Markus W. Ribbe ◽  
Britt Hedman ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Molybdenum Cofactor ◽  
X Ray ◽  
Iron Molybdenum Cofactor ◽  
X Ray Absorption

The molybdenum site of nitrogenase. 2. A comparative study of molybdenum-iron proteins and the iron-molybdenum cofactor by x-ray absorption spectroscopy

1978 ◽  
Vol 100 (12) ◽  
pp. 3814-3819 ◽  
Author(s):  
Stephen P. Cramer ◽  
William O. Gillum ◽  
Keith O. Hodgson ◽  
Leonard E. Mortenson ◽  
Edward I. Stiefel ◽  
...  
Keyword(s):  
Comparative Study ◽  
Absorption Spectroscopy ◽  
Molybdenum Cofactor ◽  
X Ray ◽  
Iron Proteins ◽  
Iron Molybdenum Cofactor ◽  
X Ray Absorption

Protonation and Sulfido versus Oxo Ligation Changes at the Molybdenum Cofactor in Xanthine Dehydrogenase (XDH) Variants Studied by X-ray Absorption Spectroscopy

2017 ◽  
Vol 56 (4) ◽  
pp. 2165-2176 ◽  
Author(s):  
Stefan Reschke ◽  
Stefan Mebs ◽  
Kajsa G. V. Sigfridsson-Clauss ◽  
Ramona Kositzki ◽  
Silke Leimkühler ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Xanthine Dehydrogenase ◽  
Molybdenum Cofactor ◽  
X Ray ◽  
X Ray Absorption

scholarly journals Selenol binds to iron in nitrogenase iron-molybdenum cofactor: an extended x-ray absorption fine structure study.

1994 ◽  
Vol 91 (4) ◽  
pp. 1290-1293 ◽  
Author(s):  
S. D. Conradson ◽  
B. K. Burgess ◽  
W. E. Newton ◽  
A. Di Cicco ◽  
A. Filipponi ◽  
...  
Keyword(s):  
Fine Structure ◽  
Structure Study ◽  
Molybdenum Cofactor ◽  
X Ray ◽  
Absorption Fine ◽  
Iron Molybdenum Cofactor ◽  
X Ray Absorption

Characterization of Radiation Damage at the Nb Site in Natural Pyrochlores and Samarskites by X-Ray Absorption Spectroscopy

1988 ◽  
Vol 127 ◽  
Author(s):  
R. B. Greegor ◽  
F. W. Lytle ◽  
B. C. Chakoumakos ◽  
G. R. Lumpkin ◽  
J. K. Warner ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Long Range ◽  
Absorption Spectroscopy ◽  
Alpha Decay ◽  
Long Range Order ◽  
Static Disorder ◽  
Annealed Condition ◽  
X Ray ◽  
X Ray Absorption

ABSTRACTX-ray absorption spectroscopy has been used to investigate the Nb B-site in pyrochlores (A1.2B2O6Y0–1, Fd3m, Z=8) and samarskites (A3B5O16) in both metamict and annealed condition. The XANES and EXAFS measurements indicate significant changes in pyrochlore and smaller changes in samarskite as a result of radiation damage. In the metamict state the Nb site in both pyrochlores and samarskites is similar to Nb in Nb2O5. Short Nb-O (1.65Å) bonds are not disrupted by alpha-decay/recoil-nuclei events as much as longer bonds (2.00Å). This increases the asymmetry and static disorder at the local Nb site while long range order is greatly diminished resulting in considerable distribution in Nb-M distances and bond angles.

scholarly journals X-ray absorption spectroscopy study of the chemistry of «invisible» Au in arsenian pyrites

2019 ◽  
Vol 98 ◽  
pp. 05007
Author(s):  
Olga Filimonova ◽  
Alexander Trigub ◽  
Maximilian Nickolsky ◽  
Elena Kovalchuk ◽  
Vera Abramova ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Valence State ◽  
Ore Deposits ◽  
Minor Amount ◽  
Published Data ◽  
Synthetic Sample ◽  
X Ray ◽  
Anion Site ◽  
A Minor ◽  
X Ray Absorption

Arsenian pyrite is an abundant mineral occurring in many geological settings at the Earth’s surface, including hydrothermal ore deposits which are the main source of Au. So-called “invisible” (or refractory) form of Au is present in pyrites in all types of these deposits, and its concentration is often directly correlated with As content. Here we report results of the investigation of the local atomic structure of Au in natural (Cu-Au-porphyry) and synthetic (450°C/ 1 kbar, 300°C/ Psat) As-free and As-bearing pyrites by means of X-ray absorption spectroscopy (XAS). In addition, the state of As was determined in pyrite samples from Carlin-type deposit. XANES/EXAFS measurements, compiled with previously published data, revealed the chemical state (valence state, local atomic environment) of Au and As in arsenian pyrites. Au is present in the solid solution state (Au1+ in the Fe position, octahedrally coordinated by S atoms), as well as in Au1+2S clusters (Au1+ linearly coordinated by 2 S atoms). The admixture of As has no effect on the Au valence state and Au-S interatomic distance, except one synthetic sample containing a minor amount of FeAsS. Arsenic mostly incorporates into the anion site in pyrite lattice (S1-↔As1-). Our data demonstrate that pyrites of hydrothermal origin can host up to ~300 ppm of structurally bound “invisible” Au independently of As content.

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