[Elastase from the hepatopancreas of the king crab].

Using ion-exchange chromatography on DEAE-Sepharose and gel-filtration on Sephacryl S-200, a homogeneous preparation of elastase with a specific activity towards Boc-(Ala)3-pNA of 3.7 u./mg has been isolated from the hepatopancreas of the king crab Paralithodes camtschatica. The molecular mass and isoelectric point for the enzyme are equal to 28500 Da and 4.5, respectively. The amino acid composition of the isolated protease has been established. Analysis of catalytic properties of the enzyme revealed that the maximal elastase activity is observed at pH 8.0-8.5; the Km and kcat values for Suc-(Ala)3-pNA are 4 mM and 3 s-1, respectively. The enzyme activity is fully inhibited by elastinal and diisopropylfluorophosphate, but not by N-ethylmaleimide, 2-mercaptoethanol, p-chloromercuribenzoate, EDTA, or o-phenanthroline, which makes it possible to refer the enzyme to the class of serine elastases. The activating effect of crab elastase was demonstrated in the presence of inorganic salts. The elastase is stable in neutral and alkaline solutions containing detergents as well as at temperatures below 45 degrees C (pH 8.0).