| he Mossbauer, EPR and redox titration techniques have been employed to study the hexaheme nitrite reductase isolated from Desulfovibrio desulfuricans(ATCC 27774). The oxidized sample and the reduced samples have been investigated under widely varying conditions. Particularly, the Mossbauer spectra of these samples have been recorded (i) over a temperature range of 4.2 K to 200 K and (ii) at 4.2 K with an applied field of zero to 80 kG. The well-established crystal-field theory for low-spin ferric complexes has been adopted to interpret the Mossbauer spectra. The characteristic parameters, namely the crystal field parameters and the magnetic hyperfine coupling constants, of each heme group in the enzyme have been obtained through a detailed analysis of the experimental data. A systematic redox titration study with redox potentials ranging from +242 mV to... |
