Jaffe E K
Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
J Bioenerg Biomembr. 1995 Apr;27(2):169-79. doi: 10.1007/BF02110032.
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 (PBGS), also known as 5-aminolevulinate dehydratase. This review documents what is known about the mechanism of the PBGS-catalyzed reaction. The metal ion constituents of PBGS are of particular interest because PBGS is a primary target for the environmental toxin lead. Mammalian PBGS contains two zinc ions at each active site. Bacterial and plant PBGS use a third metal ion, magnesium, as an allosteric activator. In addition, some bacterial and plant PBGS may use magnesium in place of one or both of the zinc ions of mammalian PBGS. 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 PBGS, an enzyme which has as yet eluded crystal structure determination.
胆色素原是所有生物四吡咯的单吡咯前体。胆色素原的生物合成涉及两分子5-氨基乙酰丙酸的不对称缩合，由胆色素原合酶（PBGS）催化，该酶也被称为5-氨基乙酰丙酸脱水酶。本综述记录了关于PBGS催化反应机制的已知信息。PBGS的金属离子成分特别受关注，因为PBGS是环境毒素铅的主要作用靶点。哺乳动物的PBGS在每个活性位点含有两个锌离子。细菌和植物的PBGS使用第三种金属离子镁作为变构激活剂。此外，一些细菌和植物的PBGS可能用镁取代哺乳动物PBGS的一个或两个锌离子。文中描述了这些金属离子使用上的系统发育差异，并对金属离子使用的进化分歧提出了合理依据。最后，我描述了关于PBGS结构的已知信息，该酶尚未通过晶体结构测定确定其结构。
