Functional characterization of Kunitz-type protease inhibitor Pr-mulgins identified from New Guinean Pseudechis australis

Abstract

Kunitz-type protease inhibitors, which consist of around 60 amino acid residues and three distinctive disulfide bridges, exhibit a broad range of physiological functions such as protease inhibitor and ion channel blocker. In this study, we identified cDNAs encoding Kunitz-type protease inhibitors, Pr-mulgins 1, 2 and 3, from the venom gland cDNA library of Papuan pigmy mulga snake (New Guinean Pseudechis australis). The deduced amino acid sequences of the Pr-mulgins are 92.4–99.3% identical with their orthologs in Australian P. australis. Pr-mulgin proteins were recombinantly prepared and subjected to inhibitory assays against proteases. Pr-mulgin 1 significantly affected matrix metalloprotease (MMP) 2; Pr-mulgins 2 and 3 showed potent inhibition to trypsin and plasma plasmin; and Pr-mulgin 2 inhibited α-chymotrypsin. Pr-mulgins 1, 2, and 3, however, had essentially no effect on Drosophila K+ channels (Shaker) and rat K+ channels (Kv 1.1).