CPM - 7-Diethylamino-3-(4´-maleimidylphenyl)-4-methylcoumarin

CPM is a widely used blue fluorescent thiol-reactive dye (Ex/Em: 384/470nm). This maleimide derivative of coumarin is essentially non-fluorescent until it reacts with thiols, making it possible to quantify thiols without a separation step. Good energy acceptor from tryptophan and a good energy donor to fluorescein. Used to monitor release of thiols and to distinguish proliferating cancer cells by nucleolar protein staining.

References: 
C.C. Chung; Assay and Drug Devel. Techn. 6(3), 361 (2008)
O. Khersonsky et al.; ChemBioChem 7(1), 49 (2006)
J.E.T. Corrie et al.; J. Chem. Soc. Trans. Perkin Trans. 1, 2975 (1994)