Evaluation of two biosynthetic pathways to δ-aminolevulinic acid in Euglena gracilis

delta-Aminolevulinic acid (ALA), which is an intermediate in the biosynthesis of chlorophyll a, can be biosynthesized via the C5 pathway and the Shemin pathway in Euglena gracilis. Analysis of the C-13-NMR spectrum of C-13-labeled methyl pheophorbide a, derived from C-13-labeled chlorophyll a biosynthesized from D-[1-C-13]glucose by E. gracilis, provided evidence suggesting that ALA incorporated in the C-13-labeled chlorophyll a was synthesized via both the C5 pathway and the Shemin pathway in a ratio of between 1.5 and 1.7 to one. The methoxyl carbon of the methoxycarbonyl group at C-13(2) of chlorophyll a was labeled with C-13. The phytyl moiety of chlorophyll a was labeled on C-P2, C-P3(1), C-P4, C-P6, C-P7(1), C-P8, C-P10, C-P11(1), C-P12, C-P14, C-P15(1) and C-P16.