porphyrin por·phy·rin (pôr'fə-rĭn)
Any of various heterocyclic compounds, derived from pyrrole, that occur universally in protoplasm, contain a central metal atom, and provide the foundation structure for hemoglobin, chlorophyll, and certain enzymes.
|porphyrin (pôr'fə-rĭn) Pronunciation Key
Any of various organic pigments containing four pyrrole rings bonded to one another. The rings form the corners of a large flat square, in the middle of which is a cavity that often contains a metal atom. Porphyrins occur universally in protoplasm and function with bound metals such as iron in hemoglobin and magnesium in chlorophyll.