2D H-1-NMR STUDIES OF OXIDIZED 2(FE4S4) FERREDOXIN FROM CLOSTRIDIUM-PASTEURIANUM

Oxidized ferredoxin from Clostridium pasteurianum, containing two Fe4S4 clusters, has been investigated using 2D H-1 NMR spectroscopy at 600 MHz. 2D NMR experiments allowed complete assignment of the sixteen isotropically shifted signals corresponding to the beta-CH2 protons of the eight metal coordinated cysteines. Geminal connectivities of Cys beta-CH2 protons were identified through magnitude COSY experiments and confirmed through 2D NOESY experiments. A few additional signals could be assigned to the corresponding alpha-CH protons. The importance of 2D experiments to achieve firm assignments of isotropically shifted signals in paramagnetic metalloproteins is stressed.