A trihexacontapeptide corresponding to the sequence 8–70 of eglin c and its related peptides were synthesized by the conventional solution method and their inhibitory activity against human leukocyte elastase, cathepsin G and α-chymotrypsin was examined. Although synthetic eglin c (41–49) inhibited cathepsin G and α-chymotrypsin (K i = 4.0 × 10−5 M and 2.0 × 10−5 M, respectively) but not leukocyte elastase, the synthetic trihexaconta-peptide potently inhibited cathepsin G, α-chymotrypsin and leukocyte elastase (K i = 1.8 × 10−9 M, 1.4 × 10−9 M and 2.2 × 10−9 M, respectively). The relationship between the stucture of eglin c and the inhibitory activity against the above enzymes is also described.
