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XAS and Pulsed EPR Studies of the Copper Binding Site in Riboflavin Binding Protein

Journal Article · · Inorganic Chemistry
DOI:https://doi.org/10.1021/ic800431b· OSTI ID:959861
Riboflavin Binding Protein (RBP) binds copper in a 1:1 molar ratio, forming a distinct well-ordered type II site. The nature of this site has been examined using X-ray absorption and pulsed electron paramagnetic resonance (EPR) spectroscopies, revealing a four coordinate oxygen/nitrogen rich environment. On the basis of analysis of the Cambridge Structural Database, the average protein bound copper-ligand bond length of 1.96 Angstroms, obtained by extended x-ray absorption fine structure (EXAFS), is consistent with four coordinate Cu(I) and Cu(II) models that utilize mixed oxygen and nitrogen ligand distributions. These data suggest a CuO3N coordination state for copper bound to RBP. While pulsed EPR studies including hyperfine sublevel correlation spectroscopy and electron nuclear double resonance show clear spectroscopic evidence for a histidine bound to the copper, inclusion of a histidine in the EXAFS simulation did not lead to any significant improvement in the fit.
Research Organization:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Organization:
Doe - Office Of Science
DOE Contract Number:
AC02-98CH10886
OSTI ID:
959861
Report Number(s):
BNL--82847-2009-JA
Journal Information:
Inorganic Chemistry, Journal Name: Inorganic Chemistry Vol. 47; ISSN 0020-1669; ISSN INOCAJ
Country of Publication:
United States
Language:
English