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  2. Porphyrin - Wikipedia

    en.wikipedia.org/wiki/Porphyrin

    With a total of 26 π-electrons, of which 18 π-electrons form a planar, continuous cycle, the porphyrin ring structure is often described as aromatic. [2] [3] One result of the large conjugated system is that porphyrins typically absorb strongly in the visible region of the electromagnetic spectrum, i.e. they are deeply colored.

  3. Heme - Wikipedia

    en.wikipedia.org/wiki/Heme

    Heme (American English), or haem (Commonwealth English, both pronounced /hi:m/ HEEM), is a ring-shaped iron-containing molecular component of hemoglobin, which is necessary to bind oxygen in the bloodstream. It is composed of four pyrrole rings with 2 vinyl and 2 propionic acid side chains. [1] Heme is biosynthesized in both the bone marrow and ...

  4. Hemoprotein - Wikipedia

    en.wikipedia.org/wiki/Hemoprotein

    Heme is bound to the protein either covalently or noncovalently or both. [2] The heme consists of iron cation bound at the center of the conjugate base of the porphyrin, as well as other ligands attached to the "axial sites" of the iron. The porphyrin ring is a planar dianionic, tetradentate ligand. The iron is typically Fe 2+ or Fe 3+. One or ...

  5. Heme A - Wikipedia

    en.wikipedia.org/wiki/Heme_a

    Heme A (or haem A) is a heme, a coordination complex consisting of a macrocyclic ligand called a porphyrin, chelating an iron atom. Heme A is a biomolecule and is produced naturally by many organisms. Heme A, often appears a dichroic green/red when in solution, is a structural relative of heme B, a component of hemoglobin, the red pigment in blood.

  6. Iron-binding proteins - Wikipedia

    en.wikipedia.org/wiki/Iron-binding_proteins

    The heme group uses four equatorial ligands in the porphyrin ring, with the two axial ligands being the histidine side chain and molecular oxygen. Heme proteins are proteins that contain a heme prosthetic group. The heme group consists of a porphyrin ring coordinated with an iron ion. Four nitrogen atoms in the porphyrin ring act as a ligand ...

  7. Protoporphyrin IX - Wikipedia

    en.wikipedia.org/wiki/Protoporphyrin_IX

    Protoporphyrin IX is an organic compound, classified as a porphyrin, that plays an important role in living organisms as a precursor to other critical compounds like heme and chlorophyll. It is a deeply colored solid that is not soluble in water.

  8. Macrocyclic ligand - Wikipedia

    en.wikipedia.org/wiki/Macrocyclic_ligand

    Heme, the active site in the hemoglobin (the metalloprotein in blood that transports oxygen), is a porphyrin that contains iron. Chlorophyll, the green photosynthetic pigment found in plants, contains a chlorin ring. Vitamin B 12 contains a corrin ring.

  9. Heterocyclic amine - Wikipedia

    en.wikipedia.org/wiki/Heterocyclic_amine

    Four pyrrole rings are joined in a ring structure called a porphyrin. The rings of porphyrin are components of hemoglobin, myoglobin, vitamin B12, chlorophyll, and cytochromes. In the centers of heme in hemoglobin, myoglobin, and cytochromes, iron is an ion; in the first two, iron ion is bound to oxygen.