Open AccessAssignment of individual heme EPR signalsof Desulfovibrio baculatus (strain 9974) tetraheme cytochrome c 3
Author(s) -
MOURA Isabel,
TEIXEIRA Miguel,
HUYNH Boi H.,
LeGALL Jean,
MOURA José J. G.
Publication year - 1988
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1988.tb14290.x
Subject(s) - strain (injury) , electron paramagnetic resonance , heme , cytochrome c , desulfovibrio , chemistry , cytochrome , crystallography , physics , biology , nuclear magnetic resonance , biochemistry , genetics , bacteria , enzyme , mitochondrion , anatomy
An EPR redox titration was performed on the tetraheme cytochrome c 3 isolated from Desulfovibrio baculatus (strain 9974), a sulfate‐reducer. Using spectral differences at different poised redox states of the protein, it was possible to individualize the EPR g ‐values of each of the four hemes and also to determine the mid‐point redox potentials of each individual heme: heme 4 (−70 mV) at g max = 2.93, g med = 2.26 and g min = 1.51; heme 3 (− 280 mV) at g max = 3.41; heme 2 (−300 mV) at g max = 3.05, g med = 2.24 and g min = 1.34; and heme 1 (−355 mV) at g mx = 3.18. A previously described multi‐redox equilibria model used for the interpretation of NMR data of D. gigas cytochrome c 3 [Santos, H., Moura, J. J. G., Moura, I., LeGall, J. & Xavier, A. V. (1984) Eur. J. Biochem. 141 , 283‐296] is discussed in terms of the EPR results.