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Observation of the Fe IV =O stretching Raman band for a thiolate‐ligated heme protein Compound I of chloroperoxidase
Author(s) -
Egawa Tsuyoshi,
Miki Hideho,
Ogura Takashi,
Makino Ryu,
Ishimura Yuzuru,
Kitagawa Teizo
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)80668-7
Subject(s) - raman spectroscopy , chemistry , photochemistry , heme , absorption band , porphyrin , oxygen , absorption (acoustics) , resonance (particle physics) , hydrogen peroxide , peroxide , materials science , organic chemistry , atomic physics , physics , optics , composite material , enzyme
The Fe IV =O stretching vibration has never been identified for a cysteine‐coordinated heme enzyme. In this study, resonance Raman and visible absorption spectra were observed simultaneously for transient species in the catalytic reaction of chloroperoxidase with hydrogen peroxide by using our original apparatus for mixed‐flow and Raman/absorption simultaneous measurements. For the first intermediate, the Fe IV =O stretching Raman band was observed at 790 cm −1 , which shifted to 756 cm −1 with the 18 O derivative, but the ν 4 band was too weak to be identified. This suggested the formation of an oxoferryl porphyrin π cation radical. The second intermediate gave an intense ν 4 band at 1,372 cm −1 but no oxygen isotope‐sensitive Raman band, suggesting oxygen exchange with bulk water.