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Identification of heme macrocycle type by near‐infrared magnetic circular dichroism spectroscopy at cryogenic temperatures
Author(s) -
Peng Qinyun,
Timkovich Russell,
Loewen Peter C.,
Peterson Jim
Publication year - 1992
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(92)81085-z
Subject(s) - porphyrin , magnetic circular dichroism , chemistry , electron paramagnetic resonance , chlorin , heme , circular dichroism , photochemistry , infrared spectroscopy , adduct , infrared , spectroscopy , cyanide , analytical chemistry (journal) , absorption spectroscopy , nuclear magnetic resonance , spectral line , crystallography , inorganic chemistry , optics , organic chemistry , quantum mechanics , physics , astronomy , enzyme
The electron paramagnetic resonance (EPR) and near‐infrared magnetic circular dichroism (MCD) spectra of the azide and cyanide adducts of nitrimyoglobin and hydroperoxidase II from Escherichia coli have been measured at cryogenic temperatures. For the first time, ligand‐to‐metal charge‐transfer transitions in the near‐infrared have been observed for an Fe(III)‐chlorin system. It is shown that near‐ultraviolet‐to‐visible region electronic spectra of ‘green’ hemes such as these are an unreliable indicator of macrocycle type. However, the combined application of EPR and near‐infrared MCD spectroscopics clearly distinguishes between the porphyrin‐containing nitrimyoglobin and the chlorin‐containing hydroperoxidase II.