THE PORPHYRIAS

Many vital functions in living systems are carried out by metal ions, which, in order to function, are chelated to porphyrins.' Because the porphyrins are basic to life, one might anticipate the possibility of spontaneous or nonenzymatic synthesis. Indeed, porphyrins have been isolated from a simple primordial soup of ammonia, methane, and water subjected to electrical discharge.^ The iron porphyrins are the hemes, and the magnesium porphyrins are the chlorophylls. These compounds serve as the prosthetic groups that permit the basic energy reactions upon which life depends. In its simplest form, the basic energy reaction involves transformation only of water; in more complex form, carbon dioxide participates.