Authors: Christelle Hureau Laurent Charlet Pierre Dorlet Florence Gonnet Lorenzo Spadini Elodie AnxolabéhèreMallart JeanJacques Girerd
Publish Date: 2006/06/07
Volume: 11, Issue: 6, Pages: 735-744
Abstract
The GGGTH sequence has been proposed to be the minimal sequence involved in the binding of a fifth CuII ion in addition to the octarepeat region of the prion protein PrP which binds four CuII ions Coordination of CuII by the N and Cprotected AcGGGTHNH2 pentapeptide P5 was investigated by using potentiometric titration electrospray ionization mass spectrometry UV–vis spectroscopy electron paramagnetic resonance EPR spectroscopy and cyclic voltammetry experiments Four different CuII complexes were identified and characterized as a function of pH The CuII binding mode switches from NO3 to N4 for pH values ranging from 60 to 100 Quasireversible reduction of the CuIIP5H−2 complex formed at pH 67 occurs at E 1/2=004 V versus Ag/AgCl whereas reversible oxidation of the CuIIP5H−3− complex formed at pH 100 occurs at E 1/2=066 V versus Ag/AgCl Comparison of our EPR data with those of the rSHaPrP90231 Burns et al in Biochemistry 426794–6803 2003 strongly suggests an N3O binding mode at physiological pH for the fifth CuII site in the proteinLC and CH acknowledge partial funding by the FatePride European Fifth PCRD project Work Package 5 http//wwwarpconsortiumorg We thank Yves Chapron for discussions and Guillaume Blain for EPR technical assistance The Conseil Régional de l’IledeFrance is acknowledged for its contribution to the acquisition of the Bruker ELEXSYS 500 EPR spectrometer We thank one of the reviewers for his constructive comments which helped improve the quality of this paper CH acknowledges Sun Un and William Rutherford CEA Saclay for allowing her to complete the work reported in the present paper
Keywords: