Zinc metallendopeptidase that cleaves preferentially on N-terminal side of aspartate-containing substrates. Hydrolyzes polypeptides on the amino-side of Asp in -Xaa-|-Asp-. Acts very slowly on -Xaa-|-Glu. Binds 1 zinc ion per subunit. O-linked glycan consists of the Man, GlcNAc, GlcU, Glc, GlcU, Rha, Man heptasaccharide.