porphobilinogen synthase activity
Definition
Target type: molecularfunction
Catalysis of the reaction: 2 5-aminolevulinate = 2 H2O + H+ + porphobilinogen. [EC:4.2.1.24, RHEA:24064]
Porphobilinogen synthase (also known as hydroxymethylbilane synthase) is a key enzyme in the heme biosynthesis pathway. It catalyzes the condensation of two molecules of δ-aminolevulinate to form porphobilinogen, a monopyrrole derivative. The reaction proceeds in two steps: 1) Formation of a Schiff base between the amino group of one δ-aminolevulinate molecule and the ε-amino group of a lysine residue in the active site of the enzyme. 2) This Schiff base then reacts with the second δ-aminolevulinate molecule, forming a cyclic intermediate that is subsequently decarboxylated to release porphobilinogen. This reaction is critical for the production of heme, a vital prosthetic group in proteins like hemoglobin, myoglobin, and cytochromes, which are essential for oxygen transport, muscle function, and cellular respiration. The enzyme utilizes a complex mechanism involving a number of key amino acid residues in its active site, including lysine, glutamate, and histidine, which participate in both substrate binding and catalysis.'
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Proteins (2)
| Protein | Definition | Taxonomy |
|---|---|---|
| Delta-aminolevulinic acid dehydratase | A delta-aminolevulinic acid dehydratase that is encoded in the genome of Escherichia coli K-12. [OMA:P0ACB2, PRO:DNx] | Escherichia coli K-12 |
| Delta-aminolevulinic acid dehydratase | A delta-aminolevulinic acid dehydratase that is encoded in the genome of human. [PRO:DNx, UniProtKB:P13716] | Homo sapiens (human) |
Compounds (6)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| succinic acid | succinic acid : An alpha,omega-dicarboxylic acid resulting from the formal oxidation of each of the terminal methyl groups of butane to the corresponding carboxy group. It is an intermediate metabolite in the citric acid cycle. Succinic Acid: A water-soluble, colorless crystal with an acid taste that is used as a chemical intermediate, in medicine, the manufacture of lacquers, and to make perfume esters. It is also used in foods as a sequestrant, buffer, and a neutralizing agent. (Hawley's Condensed Chemical Dictionary, 12th ed, p1099; McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1851) | alpha,omega-dicarboxylic acid; C4-dicarboxylic acid | anti-ulcer drug; fundamental metabolite; micronutrient; nutraceutical; radiation protective agent |
| 3-nitropropionic acid | 3-nitropropanoic acid : A C-nitro compound that is propanoic acid in which one of the methyl hydrogens has been replaced by a nitro group. 3-nitropropionic acid: succinate dehydrogenase inactivator; biosynthesized by FABACEAE plants from ASPARAGINE | C-nitro compound | antimycobacterial drug; EC 1.3.5.1 [succinate dehydrogenase (quinone)] inhibitor; mycotoxin; neurotoxin |
| aceturic acid | aceturic acid: structure N-acetylglycine : An N-acylglycine where the acyl group is specified as acetyl. | N-acetyl-amino acid; N-acylglycine | human metabolite |
| levulinic acid | 4-oxopentanoic acid : An oxopentanoic acid with the oxo group in the 4-position. levulinic acid: inhibits 5-aminolevulinic acid dehydratase; RN given refers to parent cpd; structure in Merck Index, 9th ed, #5316 | oxopentanoic acid; straight-chain saturated fatty acid | plant metabolite |
| monomethyl succinate | monomethyl succinate : A dicarboxylic acid monoester that is succinic acid in which one of the carboxy groups has been converted to its methyl ester. monomethyl succinate: RN given refers to parent cpd | dicarboxylic acid monoester; hemisuccinate | |
| 5-benzimidazolecarboxylic acid | 5-benzimidazolecarboxylic acid: structure in first source |