Identification of lysine (384) in cytochrome P-450 LM2 as functionally linked residue

Fluorescein isothiocyanate was selectively bound to the epsilon-amino group of a lysine residue of cytochrome P-450 LM2 at rho H 8.15. The decrease in the N-demethylase activity after modification evidences the functional importance of the modified group. After tryptic digestion the FITC-labeled peptide was isolated by means of HPLC and its amino acid composition determined. It was shown that the FITC-peptide can be attributed to the sequence Gly (379)- Arg (400) and that the label is selectively bound to Lys (384).