This thesis focuses on studying the effects of sirtuins, i.e. enzymes with important functions in the regulation of gene expression, especially because of their deacetylation activities. The aim of this research was to discover all the deacylation activities of each sirtuin, in order to identify new targets for sirtuins’ inhibition, useful in cancer treatment. Therefore, the activities of all seven sirtuins with various acyl lysine substrates were measured, using an enzymatic assay with LC-MS analysis and a fluorogenic assay, well-suited for high-throughput screenings. The enzymes used were obtained beforehand by protein expression and purification. Unfortunately, the project was cut short because of a shutdown, so only one sirtuin was tested and no significant result was obtained. However, in ideal conditions, the experiments would have been repeated for every sirtuin and optimized, to identify their deacylation activities. It could eventually have been followed by screenings of sirtuins’ inhibitors and by in vivo studies.