Isolation and properties of collagenolytic serine proteinase isoenzyme from king crab Paralithodes camtschatica

An electrophoretically homogeneous isoenzyme CSP-2 of collagenolytic serine proteinase has been isolated from the total preparation of king crab digestive enzymes. The molecular mass of the proteinase is 24.8 +/- 0.3 kD, pH optimum for activity is 8.5, the temperature optimum for activity is 38-40 degrees C, and the pH range of stability is 7-10. The enzyme has dual substrate specificity, but preference for positively charged amino acid residues in P(1)-position is more pronounced than in the case of the major isoenzyme. The temperature dependence of kinetic constants for synthetic substrate hydrolysis by CSP-2 has been investigated. Inhibition specificity of the enzyme is characteristic of serine proteinases but more like that of crab trypsin than that of the major CSP isoenzyme. The isolated collagenolytic proteinase also cleaves fibrinogen and fibrin and activates plasminogen. The amino acid sequence of the CSP-2 proteinase, which has been partially determined by tandem mass spectrometry, displays some similarity to the sequence of the major CSP isoenzyme.