is a heterocyclic aromatic ring
made from 4 pyrrole
subunits joined on opposite sides through 4 methine links. The ring, therefore, is completely aromatic, unlike the related corrins or chlorins. Porphyrins combine readily with metals, coordinating
with them in the central "hole". Iron
, and cobalt
containing porphyrins are known. Iron containing porphyrins are called hemes, and heme containing proteins
, or hemoproteins
, are found extensively in biochemistry.
If one of the four pyrrole subunits is reduced, a chlorin is produced, the ring structure found in chlorophyll. If two of the four pyrrole subunits are reduced, then you get a bacteriochlorin, found in some photosynthetic bacteria.
See also: porphyria