Synthesis and study on hydrolytic properties of fluorescein esters

A series of fluorescein esters of straight chain fatty acid were synthesized and applied to the fluorometric assay of lipase. The rate of change in the fluorescence of the solution, due to the production of fluorescein, was measured and correlated with enzyme activity. The hydrolytic properties of fluorescein esters were investigated. In addition, the relationship between their hydrolytic properties and the chain length of fluorescein esters was discussed in this paper. In contrast to fluorescein dibutyrate, fluorescein dilaurate was found to be a better substrate for the assay of lipase with the higher rate of hydrolysis and better Km value. As little as 0.0001 mg/ml of lipase can be detected with a relative accuracy of about 1.5%.