Hepatopancreas of king crab Paralithodes camtschatica produces a metalloprotease, which belongs to the astacin family, as cDNA cloning and sequencing showed. The metalloprotease has been purified chromatographically to apparent homogeneity. The purification factor was 16 and activity recovery was 20%. pH and temperature optimum have been determined. In its properties (molecular weight, pI, metal content) the metalloprotease is close to crayfish astacin. However, analysis of the enzyme sequences revealed differences, which account for differences in substrate specificities and imply a different activation mechanism.