Amide proton exchange in the α-amylase polypeptide inhibitor tendamistat studied by two-dimensional 1H nuclear magnetic resonance

The individual amide proton exchange rates in Tendamistat at pH 3.0 and 500C were measured by using two-dimensional αH nuclear magnetic resonance. Overall, it was found that the distribution of exchange rates along the sequence is dominated by the interstrand hydrogen bonds of the β-sheet structures. The slowly exchanging protons in the core of the two β-sheets were shown to exchange via an EX2 mechanism. Further analysis of the data indicates that different large-scale structure fluctuations are responsible for the exchange from the two β-sheets, even though the three-dimensional structure of Tendamistat appears to consist of a single structural domain