A new chymotrypsin-like serine protease involved in dietary protein digestion in a primitive animal, Scorpio maurus: purification and biochemical characterization

BACKGROUND: Most recent works on chymotrypsins have been focused on marine animals and insects. However, no study was reported in chelicerate. RESULTS: Scorpion chymotrypsin-like protease (SCP) was purified to homogeneity from delipidated hepatopancreases. The protease NH(2)-terminal sequence exhibited more than 60% monoacids identity with those of insect putative peptidases. The protease displayed no sequence homology with classical proteases. From this point of view, the protease recalls the case of the scorpion lipase which displayed no sequence homology with known lipases. The scorpion amylase purified and characterized by our time, has an amino-acids sequence similar to those of mammalian amylases. The enzyme was characterized with respect its biochemical properties: it was active on a chymotrypsin substrate and had an apparent molecular mass of 25 kDa, like the classically known chymotrypsins. The dependence of the SCP activity and stability on pH and temperature was similar to that of mammalian chymotrypsin proteases. However, the SCP displayed a lower specific activity and a boarder pH activity range (from 6 to 9). CONCLUSION: lower animal have a less evaluated digestive organ: a hepatopancreas, whereas, higher ones possess individualized pancreas and liver. A new chymotrypsin-like protease was purified for the first time from the scorpion hepatopancreas. Its biochemical characterization showed new features as compared to classical chymotrypsin-higher-animals proteases.