The metabolism of poly(γ-glutamic acid)s of nematocysts in Hydra vulgaris: Detection of two distinct hydrolytic enzymes in endoderm and in nematocysts

Poly(γ-L-glutamic acid)s (pγGA) are the major constituents of nematocysts, the capsules of stinging cells of enidarians. Two different pγGA-degradative activities are detected in tissue of the enidarian Hydra vulgaris. One is found mainly in endodermal tissue and the gastric cavity of the polyp and preferentially cleaves single C-terminal glutamic acids from the polymer. The other is restricted to nematocysts and hydrolyses the polymer randomly. Whereas the former is likely to be caused by unspecific gastric hydrolytic enzymes, the latter is highly specific for pγGA and might be catalysed by (part of) a pγGA-synthesizing enzyme.