Biological and structural properties of cyclic peptides derived from the alpha-amylase inhibitor tendamistat.

Six cyclic peptides with 5, 7, 9, 11, 13, and 15 amino acids, with the inhibitory sequence of the alpha-amylase inhibitor tendamistat, were synthesized. The 11-residue peptide inhibited porcine pancreatic alpha-amylase most potently (K1 0.29 +/- 0.09 microM). For the 11-residue peptide, the circular dichroism study suggested a preliminary relationship between its inhibitory activity and structural property.