Abstract

Proteins accelerate chemical reactions or even ensure that a substrate molecule undergoes a quite different reaction than in solution. To a large extent, these functions are determined by the structure of a specific protein. P roteins are however dynamic in structure, and conformational changes may modulate the activity of enzymes to the extent that they are switched on or off . In this colloquium I will present data collected on the enzyme POR, that demonstrate that it requires light to be activated, and light to perform catalysis. This makes POR a unique model system to control conformational changes and to study how they affect catalytic activity, including the initial ultrafast steps in catalysis.