Motivation:Protein structural families are groups of homologous proteins defined by the organization of secondary structure elements (SSEs). Nowadays, many families contain vast numbers of homologous structures and the SSEs can help to orient within them. Communities around specific protein families have even developed specialized SSE annotations, assigning always the same name to the equivalent SSEs in homologous proteins. A detailed analysis of the groups of equivalent SSEs and their variability provides an overview of the studied protein family and can be used to enrich the analysis of a particular protein at hand. Results: We developed a workflow for analysis of the secondary structure anatomy of a protein family, based on SSE annotation tool SecStrAnnotator. We applied this analysis to the model family of cytochromes P450 (CYPs)a family of important biotransformation enzymes with a community-wide used SSE annotation. We report the occurrence, typical length and amino acid sequence for the equivalent SSE groups, as well as the conservation/variability of these properties. We also suggest a generic residue numbering scheme for the CYP family. The comparison between the bacterial and eukaryotic part of the family highlights the major differences and reveals an anomalous group of bacterial CYPs with some typically eukaryotic features. This hints at possible evolutionary and functional relationships.