N-methyl Protoporphyrin IX is a transition state analog that potently inhibits protoporphyrin IX ferrochelatase (Ki = 10 nM), blocking the terminal step of the heme biosynthetic pathway. [1][2] It is used to study the effect of heme synthesis blockade in cell systems.[3][4]
Reference:
[1]. Ortiz de Montellano, P.R., Beilan, H.S., and Kunze, K.L. N-Methylprotoporphyrin IX: Chemical synthesis and identification as the green pigment produced by 3,5-diethoxycarbonyl-1,4-dihydrocollidine treatment. Proc. Natl. Acad. Sci. USA 78(3), 1490-1494 (1981).
[2]. Shi, Z., and Ferreira, G.C. Modulation of inhibition of ferrochelatase by N-methylprotoporphyrin. Biochem. J. 399(1), 21-28 (2006).
[3]. Atamna, H., Brahmbhatt, M., Atamna, W., et al. ApoHRP-based assay to measure intracellular regulatory heme. Metallomics 7(2), 309-321 (2015).
[4]. Lämsä, V., Levonen, A.-L., Sormunen, R., et al. Heme and heme biosynthesis intermediates induce heme oxygenase-1 and cytochrome P450 2A5, enzymes with putative sequential roles in heme and bilirubin metabolism: Different requirement for transcription factor nuclear factor erythroid- derived 2-like 2. Toxicol. Sci. 130(1), 132-144 (2012).