A novel hatching enzyme from starfish Asterias amurensis: purification, characterization, and cleavage specificity

Hatching enzyme (HE) is of importance to degrade egg membrane to let the larvae be free. HE was purified and characterized from starfish blastula. The specific activity and the purification ratio of the purified HE with 110.9 kDa of molecular weight were 449.62 U/mg and 7.42-fold, respectively. Its optimal pH and temperature for activity were pH 8.0 and 30 °C, respectively. This enzyme was relatively stable in the range of pH 4.0-6.0 and 30-40 °C. This enzyme was inhibited by ethylene diamine tetraacetic acid (EDTA) and ethylene glycol tetraacetic acid, and also done moderately by Leupeptin, tosyl-lysine chloromethyl ketone, tosyl-phenylalanine chloromethyl ketone, and phenyl-methanesulfonyl fluoride. Zn(2+) ion activated HE activity strongly and recovered the EDTA-pretreated activity more than did Ca(2+), Mg(2+), and Cu(2+). Based on the results above, the starfish HE was classified as a zinc metallo- and trypsin-like serine protease. The values of Km, Vmax, and Kcat of the starfish HE on dimethyl casein were 0.31 mg/ml, 0.17 U/ml, and 122.70 s(-1), respectively, whereas 1.09 mg/ml, 0.12 U/ml, and 771.98 s(-1) on type I collagen. Therefore, the starfish HE could be a potential cosmeceutical because of its strong cleavage specificity on type I collagen.