ISSN:
1432-1017
Keywords:
Iron superoxide dismutase
;
SOD
;
X-ray absorption
;
XAS
;
Extended X-ray absorption fine structure
;
EXAFS
;
P. shermanii
;
E. coli
;
Metalloproteins
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Physics
Notes:
Abstract The local structure of the iron site in ferric superoxide dismutase from P. shermanii was analyzed by X-ray absorption spectroscopy. The metal-ligand cluster of the enzyme is found to be similar to the crystallographically investigated ferric superoxide dismutase from E. coli. At pH 6.4 the enzyme is five-fold coordinated with three histidines, an aspartate and a water molecule. The average bond lengths between the metal and the histidines are about 2.10 Å, between metal and aspartate they are about 1.86 Å and between metal and water 1.96 Å. With an increase in pH a change in the coordination number from five to six is observed both in pre-edge peak and EXAFS spectra analysis. However, the bond lengths of the ligands do not change dramatically, they are conserved for the aspartate and increase slightly to 2.13 Å for the average metal - histidine distance at pH 9.3. The observation of the increase in coordination number is correlated with a decrease in enzymatic activity which occurs in the high pH range. The zinc EXAFS spectra of P. shermanii superoxide dismutase have shown that zinc can be incorporated in the active center instead of the iron.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00205105
