Modified tetrapyrroles are large macrocyclic compounds, consisting of diverse conjugation and metal chelation systems and imparting an array of colors to the biological structures that contain them. Tetrapyrroles represent some of the most complex small molecules synthesized by cells and are involved in many essential processes that are fundamental to life on Earth, including photosynthesis, respiration, and catalysis. These molecules are all derived from a common template through a series of enzyme-mediated transformations that alter the oxidation state of the macrocycle and also modify its size, its side-chain composition, and the nature of the centrally chelated metal ion. The different modified tetrapyrroles include chlorophylls, hemes, siroheme, corrins (including vitamin B12), coenzyme F430, heme d 1, and bilins. After nearly a century of study, almost all of the more than 90 different enzymes that synthesize this family of compounds are now known, and expression of reconstructed operons in heterologous hosts has confirmed that most pathways are complete. Aside from the highly diverse nature of the chemical reactions catalyzed, an interesting aspect of comparative biochemistry is to see how different enzymes and even entire pathways have evolved to perform alternative chemical reactions to produce the same end products in the presence and absence of oxygen. Although there is still much to learn, our current understanding of tetrapyrrole biogenesis represents a remarkable biochemical milestone that is summarized in this review.

中文翻译：

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改性四吡咯的生物合成——生命的色素。


改性四吡咯是大环化合物，由不同的共轭和金属螯合系统组成，并赋予包含它们的生物结构一系列颜色。四吡咯是细胞合成的一些最复杂的小分子，参与地球生命的许多基本过程，包括光合作用、呼吸和催化。这些分子均通过一系列酶介导的转化衍生自共同模板，这些转化改变了大环的氧化态，并改变了其大小、侧链组成和中心螯合金属离子的性质。不同的修饰四吡咯包括叶绿素、血红素、西罗血红素、corrins（包括维生素 B12）、辅酶 F430、血红素 d 1 和 bilins。经过近一个世纪的研究，现在几乎所有合成该化合物家族的 90 多种不同酶都已为人所知，并且重建操纵子在异源宿主中的表达已证实大多数途径是完整的。除了所催化的化学反应的高度多样性之外，比较生物化学的一个有趣的方面是观察不同的酶甚至整个途径如何进化以进行替代的化学反应，从而在有氧和无氧的情况下产生相同的最终产物。尽管还有很多东西需要学习，但我们目前对四吡咯生物发生的理解代表了本综述中总结的一个非凡的生化里程碑。