Secondary structure of the alpha-amylase polypeptide inhibitor tendamistat from Streptomyces tendae determined in solution by 1H nuclear magnetic resonance.

Complete sequence-specific 1H nuclear magnetic resonance assignments were obtained for the backbone hydrogen atoms in Tendamistat, a protein with 74 residues. From NOESY observation of 1H-1H short distance constraints, measurements of the spin-spin couplings 3JHN alpha and a qualitative identification of slowly exchanging amide protons, two antiparallel beta-sheets containing three and four strands, respectively, were identified. The peptide segments outside the beta-sheets do not form regular secondary structure. Preliminary data were obtained on the relative spatial arrangements of the two beta-sheets.