The present invention concerns a method for selectively activating a thermostable hydrolase at a temperature above T1. The present invention provides compositions comprising a thermostable hydrolase and a temperature sensitive inhibitor, wherein said thermostable hydrolase and said temperature sensitive inhibitor form a hydrolase-inhibitor complex at a temperature below T1, but which dissociates at a temperature of about T1. The present invention also relates to uses of said compositions, and a method for preparing said compositions.