Time‐resolved Fourier‐transform infrared studies of the cytochrome P‐450cam carbonmonoxide complex bound with (1R)‐camphor and (1S)‐camphor substrate

The CO‐binding reaction of cytochrome P‐450cam 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...

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Bibliographic Details
Published in:	FEBS letters 1996-03, Vol.383 (1-2), p.13-17
Main Authors:	Contzen, Jörg, Ristau, Otto, Jung, Christiane
Format:	Article
Language:	eng
Subjects:	Camphor - metabolism Camphor 5-Monooxygenase Carbon monoxide Carbon Monoxide - chemistry Carbon Monoxide - metabolism Cytochrome P-450 Enzyme System - chemistry Cytochrome P-450 Enzyme System - metabolism Cytochrome P-450cam Flash photolysis FTIR, Fourier-transform infrared Heme - metabolism Infrared Mb, myoglobin Mixed Function Oxygenases - chemistry Mixed Function Oxygenases - metabolism P-450cam(1R), (1R)-camphor bound form of cytochrome P-450cam P-450cam, cytochrome P-450 from Pseudomonas putida (CYP101) P-450nor, cytochrome P-450 from Fusarium oxysporum Spectroscopy, Fourier Transform Infrared Stereoisomerism Substrate interaction Temperature Thermodynamic parameter Thermodynamics
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Summary:	The CO‐binding reaction of cytochrome P‐450cam 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‐450cam. 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‐450cam catalyzed hydroxylation compared to 3% for the conversion of (1R)‐camphor.
ISSN:	0014-5793 1873-3468