The Enzymatic Synthesis of s=Aminolevulinic Acid*

The details of this condensation and the mechanisms involved were not elucidated until very recently. In the last few months, several laboratories have independently reported their preliminary findings demonstrating the enzymatic synthesis of 6aminolevulinic acid. We have found that particle-free extracts of Rhodopseudomonas spheroides and Rhodosp&%llum rubrum cells grown anaerobically in the light catalyze the formation of &aminolevulinic acid (5, 6). Sawyer and Smith (7) used extracts of anaerobically grown R. spheroides, whereas Gibson (8) demonstrated the synthesis in extracts of aerobically grown R. spheroides. Laver and Neuberger (9) and Gibson et al. (10) also have reported similar findings with a particulate fraction obtained from erythrocytes of phenylhydrazine-treated chickens. This communication is a more detailed report on our finding that particle-free extracts of two photosynthetic bacteria, R. spheroides and R. rubrum, are capable of catalyzing the net synthesis of d-aminolevulinic acid from succinate and glycine on addition of cofactors (CoA, ATP, pyridoxal phosphate, and Mg++ ion) or from succinyl-Coil and glycine on addition of pyridoxal phosphate. Lascelles (11) has demonstrated that not only are porphyrins synthesized by R. spheroides by the sequence of reactions previously elucidated in other cells (12), but also that porphyrins and porphobilinogen accumulate in the medium under particular growth conditions. We were encouraged to investigate this bacterium and related organisms for the enzymes responsible for the synthesis of b-aminolevulinic acid, for we found that this acid was also present in the medium after the R. spheroides cells were suspended in Medium I of Lascelles. R. spheroides and R. rubrum were grown on Medium S of Lascelles (11) under anaerobic conditions and in the light. Extracts of the harvested cells were obtained after the rupture