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Identification of axial ligands of cytochrome c 552 from Nitrosomonas europaea
Author(s) -
Arciero David M.,
Peng Qinyun,
Peterson Jim,
Hooper Alan B.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)80504-0
Subject(s) - nitrosomonas europaea , electron paramagnetic resonance , heme , chemistry , ferric , cytochrome , cytochrome c , histidine , photochemistry , crystallography , nuclear magnetic resonance , stereochemistry , biochemistry , inorganic chemistry , physics , organic chemistry , amino acid , nitrite , nitrate , mitochondrion , enzyme
Cytochrome c 552 from Nitrosomonas europaea was analyzed by visible, EPR and MCD spectroscopies. The visible and MCD data show that histidine and methionine are the axial ligands to the heme iron of the ferric protein. The EPR spectrum of the cytochrome shows an atypical highly axial low spin (HALS) type signal with g‐values that make it difficult to identify the axial ligands. These results reinforce the value of near‐infrared MCD spectroscopy for assigning ligands in ferric heme systems and point out the difficulties in using only EPR spectroscopy for the same purpose. The description of another c ‐cytochrome exhibiting a HALS‐type EPR signal will eventually be helpful in explaining the physical basis for this unusual signal.