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EXAFS reveals a structural zinc binding site in the bovine NADH‐Q oxidoreductase
Author(s) -
Giachini Lisa,
Francia Francesco,
Boscherini Federico,
Pacelli Consiglia,
Cocco Tiziana,
Papa Sergio,
Venturoli Giovanni
Publication year - 2007
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.11.019
Subject(s) - extended x ray absorption fine structure , chemistry , zinc , crystallography , flavin mononucleotide , oxidoreductase , metalloprotein , flavin group , histidine , spectroscopy , absorption spectroscopy , metal , enzyme , biochemistry , organic chemistry , physics , quantum mechanics
The metal content of bovine NADH‐Q oxidoreductase determined by inductively‐coupled plasma atomic‐emission spectroscopy reveals the presence of about one atom of zinc per molecule of flavin mononucleotide. We applied Zn K‐edge extended X‐ray absorption fine structure spectroscopy (EXAFS) to investigate the local structure of the bound zinc ion and to identify the nature of the coordinating residues. The EXAFS spectrum is consistent with a structured zinc binding site. By combining information from first‐shell analysis and from metalloprotein data bases putative binding clusters have been built and fitted to the experimental spectrum using ab initio simulations. The best fitting binding cluster is formed by two histidine and two cysteine residues arranged in a tetrahedral geometry.