Inventory of the cytochrome P450 superfamily

A non-redundant database of 325 protein sequences of the P450s has been subjected to cluster analysis. Thresholds for (sub)families have been optimized to minimize the differences between the obtained clusters and nomenclature adopted for the P450s. At the given thresholds, approximately 80% of the systematic nomenclature is reproduced by the cluster analysis. The differences primarily occur among the CYP4 and CYP6 families, which include cytochromes P450 of mammalian and insect origin. Conflicts are also encountered among plant families and among P450s of Mycobacterium tuberculosis.