9-Amino-6-chloro-2-methoxyacridine (Synonyms: ACMA)

9-Amino-6-chloro-2-methoxyacridine (ACMA) is a cell-permeable fluorescent probe that intercalates into DNA.[1] It selectively binds to poly(dA-dT) sequences with the fluorescence lifetime decreasing with incorporation of guanosine. It is used for labeling DNA and displays excitation/emission spectra of 411/475 nm, respectively.[2] ACMA fluorescence is pH-dependent and is quenched when a pH gradient is established, a property that has been utilized in animal- and plant-based studies.[3],[4],[5] It also inhibits acetylcholinesterase with a Ki value of 49 nM.[6]

Reference:
[1]. Fukui, K., Tanaka, K., Fujitsuka, M., et al. Distance dpendence of electron transfer in acridine-intercalated DNA. J. Photochem. Photobiol. B Biol. 50, 18-27 (1999).
[2]. Härd, T., Fan, P., Magde, D., et al. On the flexibility of DNA: Time-resolved fluorescence polarization of intercalated quinacrine and 9-amino-6-chloro-2-methoxyacridine. J. Phys. Chem. 93, 4338-43458 (1989).
[3]. Baracca, A., Bucchi, L., Ghelli, A., et al. Protonophoric activity of NADH coenzyme Q reductase and ATP synthase in coupled submitochondrial particles from horse platelets. Biochem. Biophys. Res. Commun. 235(3), 469-473 (1997).
[4]. Uzdavinys, P., Coinçon, M., Nji, E., et al. Dissecting the proton transport pathway in electrogenic Na+/H+ antiporters. Proc. Natl. Acad. Sci. U.S.A. 114(7), E1101-E1110 (2017).
[5]. Carqueijeiro, I., Martins, V., Noronha, H., et al. Analytical and fluorimetric methods for the characterization of the transmembrane transport of specialized metabolites in plants. Methods Mol. Biol. 1405, 121-135 (2016).
[6]. Bencharit, S., Morton, C.L., Hyatt, J.L., et al. Crystal structure of human carboxylesterase 1 complexed with the Alzheimer’s drug tacrine: From binding promiscuity to selective inhibition. Chem. Biol. 10(4), 341-349 (2003).