N-Methyl protoporphyrin IX (NmePPIX) is a derivative of protoporphyrin IX (PPIX) and the lattice of heme. Certain xenobiotics strongly induce NmePPIX production in the liver. The existence of endogenous NmePPIX in untreated animal liver has also been reported. The detailed mechanisms of NmePPIX biosynthesis remain unclear, but cytochrome P450 enzymes are thought to be critical in xenobiotic-induced NmePPIX production. High levels of NmePPIX cause PPIX accumulation because NmePPIX is a potent inhibitor (K_i = 7 nM) of ferrochelatase, the last enzyme in the heme biosynthesis pathway that converts PPIX to heme. NmePPIX is also involved in several other physiological processes, including inhibition of nitric oxide production and promotion of lamin aggregation. Compared to the two well-characterized porphyrins, PPIX and heme, NmePPIX is understudied regarding the mechanism of formation, fate, and physiological functions. This Review summarizes the current understanding of NmePPIX and provides perspectives on areas of future research on NmePPIX.

中文翻译：

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N-甲基原卟啉 IX：一种未被充分研究的卟啉

N-甲基原卟啉 IX (NmePPIX) 是原卟啉 IX (PPIX) 和血红素晶格的衍生物。某些异生素强烈诱导肝脏中 NmePPIX 的产生。还报道了在未经处理的动物肝脏中存在内源性 NmePPIX。NmePPIX 生物合成的详细机制尚不清楚，但细胞色素 P450 酶被认为在外源性诱导的 NmePPIX 生产中至关重要。高水平的 NmePPIX 导致 PPIX 积累，因为 NmePPIX 是一种有效的抑制剂 ( K _i= 7 nM) 的亚铁螯合酶，它是血红素生物合成途径中将 PPIX 转化为血红素的最后一种酶。NmePPIX 还参与其他几个生理过程，包括抑制一氧化氮的产生和促进核纤层蛋白聚集。与两种充分表征的卟啉 PPIX 和血红素相比，NmePPIX 在形成机制、命运和生理功能方面的研究不足。本综述总结了当前对 NmePPIX 的理解，并提供了对 NmePPIX 未来研究领域的观点。