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).