[29] Hatching enzyme of the sea urchin Strongylocentrotus purpuratus

Early expression of a collagenase-like hatching enzyme gene in the sea urchin embryo.

“…One of the strongest homologies between the hatching enzyme and collagenases is found in the region which contains the HEXXH motif known to be part of the active centre of the Zn2+ metalloenzymes. The presence of a zinc atom at the active centre of the hatching enzyme has not been demonstrated but it was already known that only metalloproteinase inhibitors were effective in blocking hatching activity (Barrett and Edwards, 1976; T.Lepage and C.Gache, unpublished results) and the metal ion dependence of the activity has been suggested already (Showman and Whiteley, 1980). Another striking feature is the perfect conservation of the peptide PRCGVPDV between the sea urchin enzyme and all the collagenase family members for which sequences have been published (Alexander and Werb, 1989).…”

Secretory functions of egg cortical granules in fertilization and development: A critical review

“…Since the extensive cross-inking reactions responsible for hardening of the fertilization envelope are clearly distinct from, and much more extensive than, what is necessary to promote an effective block to polyspermy, they must serve other critically important protective functions in embryogenesis. When this protection is no longer necessary, the embryo secretes a special hatching enzyme to dissolve the fertilization envelope and becomes a free-swimming organism in its aquatic environment [Barrett and Edwards, 1976;Katagiri, 1975;Yamamoto and Yamagami, 1975;Yoshizaki, 19781. Since the hardening and subsequent dispersal of the fertilization envelope (hatching) require the expenditure of a large amount of metabolic energy, this process obviously must have great survival value, and it is even conserved in mammals where fertilization and development are both internal [Denker, 1972;Dickman, 1969;Inoue and Wolf, 19751. In terms of devising new ways to regulate human reproduction, the hardening of the zona and subsequent "hatching" just prior to implantation might prove to be useful targets for the development of new nonhormonal contraceptive agents.…”

The specificity of sea urchin hatching enzyme (envelysin) places it in the mammalian matrix metalloproteinase family

“…A unit of HEz activity was defined as the activity to denude 50% embryos in 1 h at 20 OC. Caseinolytic activity was assayed by the method of Barrett and Edwards (1976) using dimethylated casein, quantifying the newly generated amino groups with trinitrobenzenesulfonic acid by measuring the absorbance at 340 nm. Glucanase activity was assayed by the method of Talbot et al (1982), using soluble laminarin as substrate and glucose oxidase and horseradish peroxidase as secondary enzymes.…”

“…These basic specificities of HEz, thus far, have not been determined. A previous report argued that HEz is specific to the carboxyl side of Glu-and Asp-residues (Barrett & Edwards, 1976). Others have claimed that HEz is chymotrypsin-like on the basis of experiments on a crude preparation of the enzyme using small substrates and inhibitors of chymotrypsin Post et al, 1988).…”