GlcN6P_deaminase: Glucosamine-6-phosphate (GlcN6P) deaminase subfamily; GlcN6P deaminase catalyzes the reversible conversion of GlcN6P to D-fructose-6-phosphate (Fru6P) and ammonium. The reaction is an aldo-keto isomerization coupled with an amination or deamination. It is the last step of the metabolic pathway of N-acetyl-D-glucosamine-6-phosphate (GlcNAc6P). GlcN6P deaminase is a hexameric enzyme that is allosterically activated by GlcNAc6P.