Thiamin pyrophosphate binding mechanism and the function of the aminopyrimidine part.

Besides the pyrophosphate group, acting as the essential and primary binding function of TPP the N1-atom of the aminopyrimidine component functions as a second and also essential anchor to the protein component. Only if both of the contacts are formed the productive conformation of TPP within the active site of TPP enzymes is realized. A mechanism is proposed, which explains the results of our experiments with TPP-analogs.