A 2D approach to obtain assignments of isotropically shifted signals in paramagnetic metalloproteins

What is it about?

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

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