ELASTASE FROM HEPATOPANCREAS OF THE KING CRAB (PARALITHODES CAMTSCHATICA)

A homogeneous preparation of elastase from the king crab Paralithodes camtschatica hepatopancreas with specific activity 3.7 units per mg pr otein toward Boc-(Ala)(3)-pNA was isolated by ion-exchange chromatogra phy on DEAE-Sepharose and gelfiltration on Sephacryl S-200. The molecu lar weight and isoelectric point of the king crab elastase are 28.5 kD and 4.5, respectively The amino acid composition of the elastase was determined The enzyme exhibits its maximal catalytic activity at pH 8. 0-8.5, the values of K-m and k(cat) toward Suc-(Ala)(3)-pNA being 4 mM and 3 sec(-1), respectively. In contrast to N-ethylmaleimide, 2-merca ptoethanol, p-chloromercuribenzoate, EDTA, and o-phenanthroline, elast inal and diisopropyl fluorophosphate completely suppress the protease activity, suggesting that the enzyme is a member of the family of seri ne elastases. Activation of the king crab elastase by inorganic salts was found The enzyme is rather stable in neutral and basic solutions a nd in the presence of surfactants at temperatures below 45 degrees C ( pH 8.0).