title: A new chymotrypsin-like serine protease involved in dietary protein digestion in a primitive animal, Scorpio maurus: purification and biochemical characterization.
abstract: 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 NH2-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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Laboratoire de Biochimie et de Génie Enzymatique des Lipases, ENIS, Université de Sfax, route de Soukra 3038, BP 1173 Sfax-Tunisia.
authors.forename: Hanen
authors.initials: H
authors.lastname: Louati
authors.forename: Nacim
authors.initials: N
authors.lastname: Zouari
authors.forename: Nabil
authors.initials: N
authors.lastname: Miled
authors.forename: Youssef
authors.initials: Y
authors.lastname: Gargouri
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002413:Cations, Divalent / Q000737:chemistry; D002850:Chromatography, Gel / Q000379:methods; D004044:Dietary Proteins / Q000378:metabolism*; D004063:Digestion; D004492:Edetic Acid / Q000737:chemistry; D057075:Enzyme Assays; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D012605:Scorpions / Q000201:enzymology*; D016415:Sequence Alignment; D057057:Serine Proteases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000737:chemistry
chemical_list: D002413:Cations, Divalent; D004044:Dietary Proteins; D015842:Serine Proteinase Inhibitors; D004492:Edetic Acid; D057057:Serine Proteases