Investigation of oxidation state-dependent conformational changes in Desulfovibrio vulgaris Hildenborough cytochrome c553 by two-dimensional H-NMR spectra.

Two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR) was used to assign the proton resonances of ferricytochrome C553 from Desulfovibrio vulgaris Hildenborough. The spin systems of 76 out of 79 amino acids were identified by J-correlation spectroscopy (COSY and HOHAHA) in H20 and D20 and correlated by nuclear Overhauser effect spectroscopy (NOESY). The proton chemical shifts are compared in both oxidized and reduced states of the protein at 23 degrees C and pH 5.9. Chemical shift variations between reduced and oxidized states are due to the paramagnetic contribution. Medium and long-range nOe demonstrate the lack of major changes between the two redox states. NMR data provide evidence that in this low oxidoreduction potential cytochrome, the oxidized state is more rigid than the reduced state.