The original map of mammalian cytochrome P450 (CYP450) residues involved in substrate recognition was prepared for the CYP2 family by Gotoh in 1992 by manual alignment of mammalian CYP450 residues with substrate recognition site (SRS) residues manually delimited from a bacterial cytochrome P450-substrate complex. Using modern structural bioinformatics tools, we have identified CYP450-ligand interactions in mammalian complexes to create a “X-ray structures” SRS map. In a parallel approach, we have built a “docking” SRS map by successful docking of 868 known substrates of 10 mammalian CYP450 isoforms and analysis of contacts made in docking solutions. We subsequently combined these maps to create a unified description of SRSs. The new map largely agrees with the original map by Gotoh with the six original SRS regions appearing in similar locations along the CYP450 sequence as in Gotohs map. However, important differences also occur: Two new SRS regions appear before SRS1 and we have assigned them as SRS1a and SRS1b; SRS1 is much bigger in our map than in Gotohs (49 aligned positions versus 28); & SRS2 and SRS3 are co-joined in our map to give a single large SRS region (60 aligned positions) we have designated as SRS(2,3), in contrast to the 9 and 10 aligned positions individually covered by SRS2 and SRS3 respectively in Gotohs original map. These differences result in the SRS zone covering 33 % of the mammalian CYP450 sequence in our map as opposed to 16 % in Gotohs map.
Keywords: Cytochrome P450, contact residues, docking complex, Gotoh's map, site of metabolism, substrate recognition site, heme-thiolate monooxygenases, isoforms, SMILES strings, LIGPLOT, Strip Salts, clustering, G-helix, polymorphisms, enantioselectivity, regioselectivity
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