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Time‐resolved Fourier‐transform infrared studies of the cytochrome P‐450 cam carbonmonoxide complex bound with (1R)‐camphor and (1S)‐camphor substrate
Author(s) -
Contzen Jörg,
Ristau Otto,
Jung Christiane
Publication year - 1996
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(96)00103-2
Subject(s) - camphor , chemistry , cytochrome , substrate (aquarium) , stereochemistry , fourier transform infrared spectroscopy , photochemistry , medicinal chemistry , organic chemistry , enzyme , oceanography , physics , quantum mechanics , geology
The CO‐binding reaction of cytochrome P‐450 cam bound with (1R)‐camphor and (1S)‐camphor are compared in the temperature region of 210–260 K using time‐resolved Fourier‐transform infrared spectroscopy with the CO stretch vibration as spectroscopic probe. For (1S)‐camphor as substrate the association of CO is slowed down by a factor of 2, while the dissociation is accelerated by a factor of 3. The CO complex for the (1S)‐camphor‐bound P‐450 is less stabilized ( ΔG =−22 kJ/mol) compared to the natural substrate (1R)‐camphor ( ΔG =−30 kJ/mol). The data are interpreted by a smaller change of the mobility of the (1S)‐camphor due to CO binding as compared to (1R)‐camphor, which would indicate a higher mobility of (1S)‐camphor already in the CO free reduced form of P‐450 cam . The higher mobility of (1S)‐camphor in the heme pocket might explain the increased uncoupling rate (hydrogen peroxide formation) of 11% [Maryniak et al. (1993) Tetrahedron 49, 9373–9384] during the P‐450 cam catalyzed hydroxylation compared to 3% for the conversion of (1R)‐camphor.