Matrix-assisted laser desorption mass spectrometry of cytochromes P450

Matrix-assisted laser desorption ionization on a time-of-flight (MALDI/TOF) mass spectrometer provides a rapid and accurate method for molecular weight determination of hydrophobic cytochrome P450 proteins (P450s). A mass accuracy of 0.075% was achieved by analysis of dialyzed P450 2B1 using bovine serum albumin (BSA) as an internal standard. The measured mass of cytochrome P450 2B2 with MALDI/TOF resulted in an average molecular weight which was higher than reported values. Immobilization procedures proved extremely effective on samples containing high concentrations of phosphate buffers.