Fig. 1.

Effect of iso[4]LGE₂ treatment on the enzymatic activity of CYP27A1 WT and mutants (A) and extent of modification (B). Properties of the CYP27A1 WT are shown in gray, and those of the K358R and K476R mutants are in blue and red, respectively. Enzyme activity data are expressed as a percentage relative to untreated controls and values are the mean ± SD from three independent experiments in which the P450s were treated with the same preparation of iso[4]LGE₂. A statistically significant difference in remaining activity over the course of isoLG treatment was found only for the K358R mutant as compared with the WT (P < 0.03) and the K476R mutant (P < 0.04). Values for the number of Lys-iso[4]LGE₂ lactam adducts are from two independent MRM assays of samples modified with the same preparation of iso[4]LGE₂. Time on the x axis is plotted in logarithmic scale.