Deacylates the non-reducing end of diacetylchitobiose (GlcNAc2). Can also use N-acetylglucosamine (GlcNAc) and N-acetylchitotriose (GlcNAc3). Probably involved in chitin degradation. H2O + N,N'-diacetylchitobiose = acetate + beta-D-glucosaminyl-(1->4)-N-acetyl-D-glucosamine Optimum pH is 8.5. Optimum temperature is 75 degrees Celsius. Activity levels at 37 and 100 degrees Celsius are 20% of that observed at the optimal temperature. Glycan degradation; chitin degradation. Homohexamer. By diacetylchitobiose (GlcNAc2). Belongs to the PIGL family.