porphyrin

(noun)

Any of a class of heterocyclic compounds containing four pyrrole rings arranged in a square; they are important in biochemistry in a form with a metal atom in the central cavity (hemoglobin with iron, chlorophyll with magnesium, etc.).

Related Terms

Examples of porphyrin in the following topics:

  • Biosynthesis of Tetrapyrroles

    • Thus, porphyrin macrocycles are highly conjugated systems.
    • The parent porphyrin is porphine, and substituted porphines are called porphyrins.
    • H2porphyrin + [MLn]2+ → M(porphyrinate)Ln-4 + 4 L + 2 H+
    • Some iron-containing porphyrins are called hemes.
    • Several other heterocycles are related to porphyrins.

  • Some Polycyclic Heterocycles

    • Porphyrin is an important cyclic tertrapyrrole that is the core structure of heme and chlorophyll.

  • Anaerobiosis and N2 Fixation

    • Interestingly, it is widely believed that leghemoglobin is the product of both the plant and the bacterium in which a protein precursor is produced by the plant and the heme (an iron atom bound in a porphyrin ring, which binds O2) is produced by the bacterium.

  • Biomolecules

    • Heme B is a porphyrin (four linked pyrrole rings) that readily binds iron, as shown.

  • Chelating Agents

    • Such chelating agents include the porphyrin rings in hemoglobin and chlorophyll.

  • Occult Blood

    • The four methods look at different properties such as antibodies, heme, globin, or porphyrins in blood, or at DNA from cellular material such as from lesions of the intestinal mucosa.