Abstract
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, Kcat 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. Zn2+ increased the enzyme activity by 167.28 %, while EDTA, TPCK, TGCK, leupeptin, PMSF, and TLCK decreased. In addition, Ca2+, Mg2+, and Cu2+ did not affect the enzyme activity. The starfish hatching enzyme activity pretreated with EDTA was recovered by Zn2+. Therefore, the starfish hatching enzyme was classified as a serine-zinc protease.
Highlights
Hatching enzyme is a protease released from hatching gland cells in hatching embryos for digesting their protective extracellular coats (Lepage and Gache 1989; Fan and Katagiri 2001; Yasumasu et al 1989a, b)
Starfish is an invertebrate belonging to the class of Asteroidea, Phylum Echinodermata, which produces a variety of secondary metabolites including steroids glycosides, anthraquinones, alklaoids, phospholipids, peptides, and fatty acids (Barkhouse et al 2007; Kurihara 1999)
The hatching enzyme with molecular weight of 86 kDa was homogeneous on the SDS-PAGE (Fig. 2a)
Summary
Hatching enzyme is a protease released from hatching gland cells in hatching embryos for digesting their protective extracellular coats (Lepage and Gache 1989; Fan and Katagiri 2001; Yasumasu et al 1989a, b). The hatching enzymes from many animal species, such as echinoderm (Lepage and Gache 1989), mammalian (Sawada et al 1990), avians (Yasumasu et al 2005), amphibians (Fan and Katagiri 2001; Kitamura and Katagiri 1998; Urch and Hedrick 1981), teleostean (Yasumasu et al 1989a, b; Kudo et al 2004; Shi et al 2010), and insect (Young et al 2000), have been studied since 1980s. Starfish has been regarded as a harmful marine animal to marine ecosystem because it causes severe loss of mussel, oyster, scallop, etc.
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