Characterization of a novel hatching enzyme purified from starfish Asterina pectinifera

Hatching enzyme is a protease which can degrade the membrane of egg. In this study, a hatching enzyme was purified from starfish (Asterina pectinifera) with 6.34 fold of purification rate, 5.04 % of yield, and 73.87 U/mg of specific activity. The molecular weight of starfish hatching enzyme was 86 kDa, which was reduced to 62 kDa after removal of N-linked oligosaccharides. The optimal pH and temperature of the hatching enzyme activity were pH 7.0 and 40 °C, respectively, while those of stability were pH 8 and 20 °C. The kinetic parameters, V (max), K (m), K(cat) and K (cat) /K (m) values were 0.197 U/ml, 0.289 mg/ml, 112.57 s(−1), and 389.52 ml/mg s, respectively. Zn(2+) increased the enzyme activity by 167.28 %, while EDTA, TPCK, TGCK, leupeptin, PMSF, and TLCK decreased. In addition, Ca(2+), Mg(2+), and Cu(2+) did not affect the enzyme activity. The starfish hatching enzyme activity pretreated with EDTA was recovered by Zn(2+). Therefore, the starfish hatching enzyme was classified as a serine-zinc protease.