Aspergilloglutamic peptidase, also called aspergillopepsin II (EC 188.8.131.52, proctase A, Aspergillus niger acid proteinase A, Aspergillus niger var. macrosporus aspartic proteinase) is a proteolytic enzyme. The enzyme was previously thought be an aspartic protease, but it was later shown to be a glutamic protease with a catalytic Glu residue at the active site, and was therefore renamed aspergilloglutamic peptidase.
Determination of its molecular structure showed it to be a unique two-chain enzyme with a light chain and a heavy chain bound non-covalently with each other. The C-terminal region of the light chain of one molecule binds to the active site cleft of another molecule in the manner of a substrate.
This enzyme catalyses the following chemical reaction
Preferential cleavage in B chain of insulin: Asn3
This enzyme is isolated from Aspergillus niger var. macrosporus.