FIGURE 4.

Enzymatic activity assays of murine and macaque BCO2. A, HPLC analysis of lipid extracts isolated from in vitro enzyme assays of recombinant murine (left) and macaque (right) BCO2s and zeaxanthin (Z). B, the resulting oxidative cleavage products 10Apo and 3-hydroxy-β-ionone (β-io) as well as the substrate were identified in part by retention time and known absorption spectra. Mass spectra (left and right, murine and macaque, respectively) from extracted ion chromatograms identifying the peaks at ∼10 min with an m/z of 393.28 as 10Apo (right inset) (C) and the peaks at ∼16 min with an m/z os 209.18 as 3-hydroxy-β-ionone (right inset) (D) are shown. mAU, milli-absorbance units.