Biophys J, June 1998, p. 3241-3249, Vol. 74, No. 6

Fatty Acid-Induced Alteration of the Porphyrin Macrocycle of Cytochrome P450 BM3

 ^*Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, and  ^#Department of Biochemistry, University of Glasgow, Glasgow G2 8QQ, Scotland

Surface-enhanced resonance Raman scattering (SERRS) of substrate-free and substrate-bound forms of the P450 domain of cytochrome P450 BM3 are reported and assigned. Substrate-free P450 yields mixed spin heme species in which the pentacoordinate high-spin arrangement is dominant. The addition of laurate or palmitate leads to an increase in high spin content and to an allosteric activation of heme mode ₂₉, which is sensitive to peripheral heme/protein interactions. Differences between laurate and palmitate binding are observed in the relative intensities of a number of bands and the splitting of the heme vinyl modes. Laurate binding to P450 results in different protein environments being experienced by each vinyl mode, whereas palmitate binding produces a smaller difference. The results demonstrate the ability of SERRS to probe substrate/prosthetic group interactions within an active site, at low protein concentrations.

Biophys J, June 1998, p. 3241-3249, Vol. 74, No. 6
© 1998 by the Biophysical Society   0006-3495/98/06/3241/09  $2.00