Metalloprotease that shows high activities on basic nuclear substrates such as histone and protamine. Preferential cleavage of bonds with hydrophobic residues in P1'. Also 3-Asn-|-Gln-4 and 8-Gly-|-Ser-9 bonds in insulin B chain. Binds 1 zinc ion per subunit. Thermostable. Belongs to the peptidase M35 family.