Open AccessOxalate as synergistic anion for Cd(II) binding to ovotransferrin
Author(s) -
SOLA Marco
Publication year - 1990
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1990.tb15625.x
Subject(s) - ovotransferrin , oxalate , chemistry , bicarbonate , derivative (finance) , nuclear magnetic resonance spectroscopy , metal , inorganic chemistry , carbon 13 nmr , metal ions in aqueous solution , adduct , transferrin , stereochemistry , organic chemistry , biochemistry , financial economics , economics
The Cd(II) derivative of ovotransferrin containing oxalate as synergistic anion was investigated through 113 Cd‐ and 13 C‐NMR spectroscopy and compared with the analogous derivative obtained in the presence of bicarbonate. Cadmium loaded in the C site gives rise to a 113 Cd‐NMR signal at 54 ppm, while that bound to the N site is broadened beyond detection. The two resonances at 168.5 and 169.9 ppm observed in the 13 C‐NMR spectrum of the Cd 2 derivative obtained with [ 13 C]oxalate each correspond to slowly exchanging oxalate specifically bound to a single site. No splitting of these resonances due to 113 Cd– 13 C magnetic coupling is observed upon insertion of 113 Cd‐enriched Cd(II) ion, unlike previous observations for the corresponding derivative obtained with bicarbonate as synergistic anion. It was found that the metal sites in the present derivative are inequivalent, as observed for other metal‐transferrin‐oxalate adducts. The C site is found to be sensitive to a residue ionization with a p K a of 9.5.