The Structure of the Metal Site in Rhus vernicifera Stellacyanin: A Paramagnetic NMR Study on its Co(II)-derivative

VILA, AJ; FERNANDEZ, C O

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

AMER CHEMICAL SOC

Año: 1996 vol. 118 p. 7291 - 7298

0002-7863

The 1H NMR spectrum of Co(II)-substituted stellacyanin from Rhus Vernificera has been recorded and the hyperfine-shifted signals corresponding to metal ligands have been assigned by means of 1D and 2D NOE spectra. Two His and a Cys coordinate the metal ion, and a Gln residue is the axial metal ligand. The beta-CH2 Cys proton shifts reflect a decreased electron delocalization onto this residue when compared to azurin. Both His residues are solvent accessible. This fact could contribute to the low redox potential of this protein. This work provides the first experimental evidence of a Gln coordination to the metal in a native blue copper protein.