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| PORPHOBILINOGEN SYNTHASE, THE FIRST SOURCE OF HEME SYMMETRY |
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| Author(s): JAFFE EK |
| Source: JOURNAL OF BIOENERGETICS AND BIOMEMBRANES Volume: 27 Issue: 2 Pages: 169-179 Published: APR 1995 |
| Times Cited: 85 References: 77 |
| Abstract: Porphobilinogen is the monopyrrole precursor of all biological tetrapyrroles. The biosynthesis of porphobilinogen involves the asymmetric condensation of two molecules of 5-aminolevulinate and is carried out by the enzyme porphobilinogen synthase (PEGS), also known as 5-aminolevulinate dehydratase. This review documents what is known about the mechanism of the PBGS-catalyzed reaction. The metal ion constitutents of PEGS are of particular interest because PEGS is a primary target for the environmental toxin lead. Mammalian PEGS contains two zinc ions at each active site. Bacterial and plant PEGS use a third metal ion, magnesium, as an allosteric activator. In addition, some bacterial and plant PEGS may use magnesium in place of one or both of the zinc ions of mammalian PEGS. These phylogenetic variations in metal ion usage are described along with a proposed rationale for the evolutionary divergence in metal ion usage. Finally, I describe what is known about the structure of PEGS, an enzyme which has as yet eluded crystal structure determination. |
| Document Type: Review |
| Language: English |
| Reprint Address: JAFFE, EK (reprint author), FOX CHASE CANC CTR, INST CANC RES, PHILADELPHIA, PA 19111 USA |
| Publisher: PLENUM PUBL CORP, 233 SPRING ST, NEW YORK, NY 10013 |
| Subject Category: Biophysics; Cell Biology |
| IDS Number: RK201 |
| ISSN: 0145-479X |
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| | | | | | | | | Record from Web of Science® | | | | | | | | | |