The mechanism of enzyme regulation through conformational changes is a key pattern in governing cell behavior. In this thesis the focus is on three different protein complexes that reflect how protein activity can be regulated by different effectors. Different spectroscopic techniques, like IR and Raman spectroscopy, were used is order to follow the secondary and tertiary conformational changes in protein structure to identify their roles.The regulation of protein function through conformational changes is ruled by different factors where the effectors usually target specific amino acids that trigger a cascade reaction through other regions or domains of the protein. An interesting fact obtain from the result summary is that the far infrared region can become a new approach for the study of protein function. This work adds evidence that conformational transitions are more widespread than previously thought and that structural plasticity is essential for the biological activity ofproteins.