Low molecular mass inhibitors of bovine beta-trypsin containing binding loop fragment of CMTI-III. Synthesis and evaluation of inhibitory activity

Three peptides with sequences related to the binding loop of Cucurbita maxi ma trypsin inhibitor III were obtained: [G(3),G(10)]CMTI-III (1 - 10) (1), [A(1),G(3),A(9),G(10)]CMTI-III (1 - 10) (2) and c(K-A-A-P-R-I-L-M-K-Y-A-E) (3). Ali peptides were synthesized by the solid-phase method using the Fmoc /Bu-t procedure. Peptide 1 revealed a relatively high inhibitory activity ( association equilibrium constant with bovine beta -trypsin K-a = 4 x 10(9) [M-1]). Significantly lower activity (K-n = 3.6 x 10(4) [M-1]) was obtained for peptide 3. Peptide 2 appeared to be inactive.