All structures of cytochrome P450s have been compared in the coordinate frame associated with the heme plane. Coordinates were obtained from Protein Data Bank, formatted into numerical matrix and transformed to the new frame with the XY plane as the mean plane through the 20 pyrrol atoms of the heme, and the origin at the center of gravity of the same 20 atoms.
Coordinate transformation and alignment have been performed using MATLAB.
This coordinate frame is common for all cytochrome P450s and thus allows for comparison of the structural features of the proteinmatrix shaping the active center and substrate binding pocket in the vicinity of catalytically active site.
Superposition of the X-ray structures of different cytochrome P450s in this coordinate frame provides a straight forward approach for identification of conserved and variable regions of the protein which define
substrate affinity and region-specificity of catalysis.