What enzyme activity? Dansylated derivatives are soluble in organic solvents, and these solvents are not appropriate for the maintenance of enzyme activity
According to this web page (http://focusbiomolecules.com/dansylcadaverine-autophagic-vacuole-dye/), it is soluble at 10 mg/ml in methanol, and at 10 mg/ml in DMSO with warming. The maximal concentration in your experiment will be limited by the sensitivity of your enzyme to organic solvent.