Abstract:By feeding (l-13C)-glutamic acid to Euglena gracilis, a green alga, the 13C-NMR spectra, of chlorophyll showed that the entire carbon skeleton of glutamic acid was incorporated into chlorophyll. The existence of cspathway in chlorophyll biosynthesis was proved. In cell-free test, porphobilinogen (PBG) was formed from (5-13C)-δ-aminolaevulinic acid(ALA), but no evidence for (2-13C)-glycine incorporation was observed. It means that the Shemin pathway was effectivelessness, at least, in E. gracilis.