Detection of D-Xylose Isomerase on Disc Electrophoresis

D-Xylose isomerase was crytallized from Lactocillus brevis cultered in a medium containing D-xylose. Protein fractions obtained at various steps of the purification were analyzed by disc electrophoresis. D-Xylose isomerase activity was detested in the disc gels utilizing the formation of formazan dye from triphenyltetrazolium chloeide by ketose. The crystalline preparation of the enzyme was pure on disc electrophoresis and found to catalyze the isomerization of other D-sugars: D-arabinose, D-ribose, D-glucose, D-mannose, and D-galactose. L-Arabinose was found tobe isomerized by another fraction than D-xylose isomerase.