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Spectroscopic identification of the heme axial ligation of cytochrome b 558 in the NADPH oxidase of porcine neutrophils
Author(s) -
H Fujii,
M G Finnegan,
T Miki,
B R Crouse,
K Kakinuma,
M K Johnson
Publication year - 1995
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(95)01372-5
Subject(s) - porphyrin , heme , electron paramagnetic resonance , chemistry , hemeprotein , heme a , cytochrome c oxidase , magnetic circular dichroism , resonance raman spectroscopy , cytochrome c , cytochrome , histidine , nuclear magnetic resonance , raman spectroscopy , photochemistry , circular dichroism , oxidase test , stereochemistry , biochemistry , enzyme , mitochondrion , physics , astronomy , optics , spectral line
The combination of electron paramagnetic resonance (EPR), near‐infrared magnetic circular dichroism (NIR‐MCD) and resonance Raman (RR) spectroscopies at cryogenic temperatures has been used to identify the axial heme ligation of the low spin cytochrome b 558 component of NADPH oxidase from porcine blood neutrophils. The EPR and NIR‐MCD results indicate the presence of two distinct forms in frozen solution; one with a low field g ‐value at 3.23 and porphyrin(π)‐to‐Fe(III) charge transfer maximum at 1660 nm and the other a low field g ‐value at 3.00 and porphyrin(π)‐to‐Fe(III) charge transfer maximum at 1510 nm. On the basis of these properties and the RR studies, both are attributed to forms of cytochrome b 558 with bis‐histidine axial ligation. The origin of the observed heterogeneity, the location and identity of the specific histidines involved in ligating the heme, and the role of the heme prosthetic group in O 2 − production are discussed in light of these results.