Catalyzes the isomerization of sulfoquinovose (SQ) to 6-deoxy-6-sulfo-D-fructose (SF). In vitro, can also catalyze the interconversion of mannose, fructose and glucose, or lyxose and xylulose, but has extremely low activity with glucose. 6-sulfo-beta-D-quinovose = 6-deoxy-6-sulfo-D-fructose Significantly inhibited by Cu(2+), Fe(3+) and Co(2+). Partially inhibited by Mg(2+), Ca(2+) and Mn(2+). Also inhibited by ATP, ADP, dATP, TTP and GTP. kcat is 25.3 sec(-1) for D-mannose. kcat is 22.2 sec(-1) for D-fructose. kcat is 13.5 sec(-1) for D-lyxose. kcat is 10.3 sec(-1) for D-xylulose. Optimum pH is 7. Optimum temperature is 47 degrees Celsius. Homohexamer. Induced during growth with sulfoquinovose. Mutant fails to grow on sulfoquinovose as a sole carbon source. Belongs to the N-acylglucosamine 2-epimerase family. Extended N-terminus.