Porphyrin biosynthesis is the enzyme-mediated construction of tetrapyrrole macrocycles through pathways that generate porphyrins and their derivatives. In the mammalian heme pathway, 5-aminolevulinate synthase supplies the initial precursor, and its expression links pathway activity to nutritional regulation [1]. Regulatory interactions can also connect precursor synthesis with the circadian transcriptional system [2]. Maturation of aminolevulinate synthase includes acquisition of its catalytic cofactor, supported by mitochondrial protein machinery. Aminolevulinate dehydratase then condenses precursor molecules into porphobilinogen [3][4]. Successive reactions join four porphobilinogen units into a linear tetrapyrrole and cyclize it to uroporphyrinogen III. Later transformations alter side chains and oxidation state, producing the porphyrin framework that can receive a metal ion during formation of downstream metallated products [5].