Spectroscopic characterization of cytochrome P450 Compound I

► Spectroscopic studies on Compound I (Cpd I) of cytochrome P450 are reviewed. ► The spectroscopic methods are explained and data are related to the P450 mechanism. ► In conclusion, research will no further deal with proving the existence of Cpd I. ► Future studies will focus on uncovering structural requirements to trap Cpd I.