H2O + N-{alpha-Glc-(1->3)-alpha-Man-(1->2)-alpha-Man-(1->2)-alpha-Man-(1->3)-[alpha-Man-(1->2)-alpha-Man-(1->3)-[alpha-Man-(1->2)-alpha-Man-(1->6)]-alpha-Man-(1->6)]-beta-Man-(1->4)-beta-GlcNAc-(1->4)-beta-GlcNAc}-L-asparaginyl-[protein] = alpha-D-glucosyl-(1->3)-D-mannopyranose + N(4)-{alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-[alpha-D-Man-(1->2)-alpha-D-Man-(1->3)-[alpha-D-Man-(1->2)-alpha-D-Man-(1->6)]-alpha-D-Man-(1->6)]-beta-D-Man-(1->4)-beta-D-GlaNAc-(1->4)-beta-D-GlcNAc}-L-asparaginyl-[protein] (N-glucan mannose isomer 8A1,2,3B1,2) Belongs to the glycosyl hydrolase 99 family.