Before the last set of test wells were filled, the Schlenk flask was grasped manually and briefly moved gently in a circular manner, with a radius of about 15 cm, to allow for improved exposure of the enzyme to xenon. Since the dissolution of xenon in water is an endergonic process, it is poorly soluble in water ; this gentle manual mixing 9 facilitated the ability of xenon to contact the furin enzyme, without causing enzyme denaturation. The black, 96-well, non-binding surface microplate was subsequently placed in our Tecan Infinite F200 microplate reader (Tecan Group Ltd: Männedorf, Switzerland) and underwent automatic fluorescence measurements every 5 minutes for 24 hours. The findings from these final set of test wells are presented in Figure and Figure . An initial subset of these findings is also presented in Table .