The use of Cd-113 NMR chemical shifts as a structural probe in tetrathiolate metalloproteins

摘要

A wide range of Cd-113 chemical shifts has been observed for Cd-113-substituted metalloproteins ranging from -100 ppm, for Cd with octahedral oxygen ligands, to +760 ppm for tetrahedral sulfur ligands. In particular the Cd-113 chemical shifts of tetrahedral sulfur bound sites, for proteins such as rubredoxin and desulforedoxin, appear around 720-745 ppm, New Cd-113 chemical shift data for Cd-113-substituted, overexpressed and mutated homologous desulforedoxin-like Fe(S-Cys)(4) proteins, have been obtained and a correlation between the Cd-113 chemical shift and structure at the metal site has been observed. This subtle effect of geometry at the metal centre on Cd-113 chemical shifts can be explained in terms of an increase in the paramagnetic term for the chemical shift of the Cd-113 nucleus as distortion of the tetrathiolate centre is increased. (C) 1998 Elsevier Science S.A. All rights reserved. [References: 50]