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| Identifiers | |
|---|---|
| MeSH | Uroporphyrinogen+III |
PubChem CID | |
CompTox Dashboard (EPA) | |
| Properties | |
| C40H44N4O16 | |
| Molar mass | 836.795 g/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
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| Infobox references | |
Uroporphyrinogen III is a tetrapyrrole, the first macrocyclic intermediate in the biosynthesis of heme, chlorophyll, vitamin B12, and siroheme. It is a colorless compound, like other porphyrinogens. [1]
The molecular structure of uroporphyrinogen III can be described as a hexahydroporphine core, where each pyrrole ring has the hydrogen atoms on its two outermost carbons replaced by an acetic acid group (−CH
2−COOH, "A") and a propionic acid group (−CH
2−CH
2−COOH, "P"). The groups are attached in an asymmetric way: going around the macrocycle, the order is AP-AP-AP-PA.
In the general porphyrin biosynthesis pathway, uroporphyrinogen III is derived from the linear tetrapyrrole preuroporphyrinogen (a substituted hydroxymethylbilane) by the action of the enzyme uroporphyrinogen-III cosynthase. [2] [3]
The conversion entails a reversal of the last pyrrole unit (thus swapping the acetic and propionic acid groups) and a condensation reaction that closes the macrocycle by eliminating the final hydroxyl −OH with a hydrogen atom of the first ring.
In the biosynthesis of hemes and chlorophylls, uroporphyrinogen III is converted into coproporphyrinogen III by the enzyme uroporphyrinogen III decarboxylase. In the biosynthesis of sirohemes, uroporphyrinogen III is converted by two methyl transferases to dihydrosirohydrochlorin, which is subsequently oxidized sirohydrochlorin, a precursor to the siroheme prosthetic group.
If uroporphyrinogen-III synthase is not present or inactive, the hydroxymethylbilane will spontaneously cyclise into the structural isomer uroporphyrinogen I, which differs from the III isomer in that the acetic acid ("A") and propionic acid ("P") groups are arranged in a rotationally symmetric order, AP-AP-AP-AP. In this case, the next step produced coproporphyrinogen I, which accumulates — leading to the pathological condition congenital erythropoietic porphyria [3]
Porphyrins are a group of heterocyclic macrocycle organic compounds, composed of four modified pyrrole subunits interconnected at their α carbon atoms via methine bridges (=CH−). The parent porphyrin is porphine, a rare chemical compound of exclusively theoretical interest. Substituted porphines are called porphyrins. 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. 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. The name "porphyrin" derives from the Greek word πορφύρα (porphyra), meaning purple.
Tetrapyrroles are a class of chemical compounds that contain four pyrrole or pyrrole-like rings. The pyrrole/pyrrole derivatives are linked by, in either a linear or a cyclic fashion. Pyrroles are a five-atom ring with four carbon atoms and one nitrogen atom. Tetrapyrroles are common cofactors in biochemistry and their biosynthesis and degradation feature prominently in the chemistry of life.
Porphobilinogen deaminase (hydroxymethylbilane synthase, or uroporphyrinogen I synthase) is an enzyme (EC 2.5.1.61) that in humans is encoded by the HMBS gene. Porphobilinogen deaminase is involved in the third step of the heme biosynthetic pathway. It catalyzes the head to tail condensation of four porphobilinogen molecules into the linear hydroxymethylbilane while releasing four ammonia molecules:
Uroporphyrinogen III synthase EC 4.2.1.75 is an enzyme involved in the metabolism of the cyclic tetrapyrrole compound porphyrin. It is involved in the conversion of hydroxymethyl bilane into uroporphyrinogen III. This enzyme catalyses the inversion of the final pyrrole unit of the linear tetrapyrrole molecule, linking it to the first pyrrole unit, thereby generating a large macrocyclic structure, uroporphyrinogen III. The enzyme folds into two alpha/beta domains connected by a beta-ladder, the active site being located between the two domains.
Porphobilinogen is an organic compound that occurs in living organisms as an intermediate in the biosynthesis of porphyrins, which include critical substances like hemoglobin and chlorophyll. The name is often abbreviated PBG.
Coproporphyrinogens are tetrapyrroles with four propionic acid groups and an equal number of substituted methyls.
Coproporphyrinogen III is a metabolic intermediate in the biosynthesis of many compounds that are critical for living organisms, such as hemoglobin and chlorophyll. It is a colorless solid.
Uroporphyrinogens are cyclic tetrapyrroles with four propionic acid groups and four acetic acid groups.
Protoporphyrinogen IX is an organic chemical compound which is produced along the synthesis of porphyrins, a class of critical biochemicals that include hemoglobin and chlorophyll. It is a direct precursor of protoporphyrin IX.
Hydroxymethylbilane, also known as preuroporphyrinogen, is an organic compound that occurs in living organisms during the synthesis of porphyrins, a group of critical substances that include hemoglobin, myoglobin, and chorophyll. The name is often abbreviated as HMB.
Protoporphyrin IX is an organic compound, specifically a porphyrin, that plays an important role in living organisms as a precursor other critical compounds like hemoglobin and chlorophyll. It is a deeply colored solid that is not soluble in basic water. The name is often abbreviated as PPIX.
In organic chemistry, bilane is a compound with the formula C
19H
20N
4 or [(C
4H
4N)−CH
2−(C
4H
3N)−]
2CH
2. It is a tetrapyrrole, a class of compounds with four independent pyrrole rings. Specifically, the molecule can be described as four pyrrole molecules C
4H
5N connected in an open chain by three methylene bridges −CH
2− at carbons adjacent to the nitrogens, replacing the respective hydrogens.
Uroporphyrinogen I is an isomer of uroporphyrinogen III, a metabolic intermediate in the biosynthesis of heme. A type of porphyria is caused by production of uroporphyrinogen I instead of III.
Coproporphyrinogen I is an isomer of coproporphyrinogen III, a metabolic intermediate in the normal biosynthesis of heme. The compound is not normally produced by the human body; its production and accumulation causes a type of porphyria.
Siroheme is a heme-like prosthetic group at the active sites of some enzymes to accomplish the six-electron reduction of sulfur and nitrogen. It is a cofactor at the active site of sulfite reductase, which plays a major role in sulfur assimilation pathway, converting sulfite into sulfide, which can be incorporated into the organic compound homocysteine.
F430 is the prosthetic group of the enzyme methyl coenzyme M reductase (MCR). MCR catalyzes the release of methane in the final step of methanogenesis:
In biochemistry a porphyrinogen is a member of a class of naturally occurring compounds with a tetrapyrrole core, a macrocycle of four pyrrole rings connected by four methylene bridges. They can be viewed as derived from the parent compound hexahydroporphine by the substitution of various functional groups for hydrogen atoms in the outermost (20-carbon) ring.
Sirohydrochlorin (SHC) is a macrocyclic metabolic intermediate in the biosynthesis of corrin, precursor to the tetrapyrrole pigment and cofactor F430. It is a yellow compound. Its biosynthetic precursor is dihydrosirohydrochlorin, which in turn is derived from uroporphyrinogen III. It is also the precursor to the siroheme, the prosthetic group in a sulfite reductase.
In biochemistry, chelatases are enzymes that catalyze the insertion ("metalation") of naturally occurring tetrapyrroles. Many tetrapyrrole-based cofactors exist in nature including hemes, chlorophylls, and vitamin B12. These metallo cofactors are derived by the reaction of metal cations with tetrapyrroles, which are not ligands per se, but the conjugate acids thereof. In the case of ferrochelatases, the reaction that chelatases catalyze is:
Hexahydroporphine is an organic chemical compound with formula C
20H
20N
4. The molecule consists of four pyrrole rings connected by methylene bridges −CH
2− into a larger (non-aromatic) macrocycle ring, which makes it one of the simplest tetrapyrroles, and the simplest "true" one. As indicated by the name, it may be viewed as derived from porphine by the addition of six hydrogen atoms: four on the methine bridges, and two on the nitrogen atoms.
