1,6-Hexanediol, commonly used to dissolve liquid–liquid phase separated condensates, directly impairs kinase and phosphatase activities

The concept of liquid–liquid phase separation (LLPS) has emerged as an intriguing mechanism for the organization of membraneless compartments in cells. The alcohol 1,6-hexanediol is widely used as a control to dissolve LLPS assemblies in phase separation studies in diverse fields. However, little is known about potential side effects of 1,6-hexanediol, which could compromise data interpretation and mislead the scientific debate. To examine this issue, we analyzed the effect of 1,6-hexanediol on the activities of various enzymes in vitro. Already at 1% volume concentration, 1,6-hexanediol strongly impaired kinases and phosphatases and partly blocked DNA polymerases, while it had no effect on DNase activity. At concentrations that are usually used to dissolve LLPS droplets (5–10%), both kinases and phosphatases were virtually inactive. Given the widespread function of protein phosphorylation in cells, our data argue for a careful review of 1,6-hexanediol in phase separation studies.