2003 Volume 20 Issue 1 Pages 93-96
A 20-kDa protein (p20) having 40% sequence similarity with Kunitz-type soybean trypsin inhibitor (STI) from Glycine max (soybean) cultured cells was expressed in Escherichia coli. The recombinant p20 (rp20) inhibited the activity of trypsin at the same level as STI (rp20, Ki=50nM; STI, Ki=75nM), and both rp20 and STI displayed non-competitive inhibition of trypsin activity. Although STI inhibited the activity of α-chymotrypsin (Ki=140nM) and elastase (Ki=207nM), rp20 did not inhibit the activity of α-chymotrypsin and elastase. These results show that p20 is a novel type of trypsin inhibitor.
