800 MHZ H-1-NMR SOLUTION STRUCTURE REFINEMENT OF OXIDIZED CYTOCHROME C(7) FROM DESULFUROMONAS ACETOXIDANS

The solution structure of Desulfuromonas acetoxidans cytochrome c(7) h as been refined by using H-1-NMR spectra recorded at 800 MHz and by us ing pseudocontact shifts in the final energy minimization procedure. T he protein, composed of 68 amino acids, contains three paramagnetic he me moieties, each with one unpaired electron. The largely distributed paramagnetism broadens the lines in several protein parts. The structu re is now relatively well resolved all over the backbone by the use of 1315 meaningful NOEs and 90 pseudocontact shifts. The statistical ana lysis of the structure indicates its satisfactory quality. The protein -fold is quite similar to that of the analogous four-heme cytochromes c(3) for those parts which can be considered homologous. The solvent a ccessibility and the electrostatic potential surfaces surrounding the three hemes have been analyzed in terms of their reduction potentials. The resulting magnetic susceptibility anisotropy data obtained from p seudocontact shifts are analyzed in terms of structural data.