EXAFS investigation of the active site of iron superoxide dismutase of Escherichia coli and Propionibacterium shermanii

C. Scherk, M. Schmidt, H. F. Nolting, B. Meier, F. Parak

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

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.

Original languageEnglish
Pages (from-to)243-250
Number of pages8
JournalEuropean Biophysics Journal
Volume24
Issue number4
DOIs
StatePublished - Apr 1996

Keywords

  • E. coli
  • EXAFS
  • P. shermanii
  • SOD
  • X-ray absorption
  • XAS
  • extended X-ray absorption fine structure
  • iron superoxide dismutase
  • metalloproteins

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