Molecular machines such as kinesin or spastin are enzymes that facilitate biochemical reactions involving mechanical actions. Still, they obey fundamental principles of bio-catalysis, such as kinetic laws and inhibition reactions. We are studying the pathways of transition states of enzymatic reactions using kinetic assays. A valuable tool are inhibitors that 'freeze' the reaction at a specific point. We see the future of this field in elucidating the conformational fluctuations of an enzyme during its catalytic cycle (e.g. by fluorescence resonance transfer reactions) and thus focus on methods that resolve transitions in time.