Figure 4.

Recombinant human BCO2 converts β-carotene to β-apo-10′-carotenal. Recombinant human 579-aa BCO2 isoform was expressed in β-carotene producing E. coli. Lipids were extracted and subjected to LC-MS analyses. Putative apocarotenal cleavage products were converted to the corresponding oximes (syn and anti) by hydroxylamine. A) LC-MS diagram at m/z 392 of lipid extracts isolated from cells expressing BCO2 (black trace) as compared to cells that lack BCO2 expression (red trace). B) LC-MS diagram of a β-apo-10′-carotenal standard was extracted under the same conditions to verify the retention time, absorbance spectra, and mass. Insets on the right show MS/MS fragmentation patterns of 392 m/z peak of the E. coli extract and the β-apo-10′-carotenaloxime standard, respectively.