ESCHERICHIA-COLI PHOSPHORYLATES 1,5-ANHYDROGLUCITOL AND RELEASES 1,5-ANHYDROGLUCITOL 6-PHOSPHATE WHEN GLUCOSE IS ABSENT IN THE MEDIUM

The cyclic polyol 1,5-anhydro-D-glucitol (AG) is detected in most orga nisms, but little is known about its metabolism and physiological role s. Our previous study demonstrated that Escherichia coli C600 synthesi zes AG when glucose is exhausted in the medium and that it temporarily releases AG into and then takes it back from the medium, thus forming a sharp peak in AG concentration in the medium a few hours after reac hing stationary growth phase. The present study demonstrates that when glucose is absent in the culture medium, E. coli C600 takes up and ph osphorylates AG and releases a large portion of it back into the mediu m in the form of a phosphate ester. [U-C-13]AG was added to the medium after the exhaustion of glucose and the resulting [U-C-13]AG phosphat e was partially purified by several steps of anion exchange chromatogr aphy and identified as AG 6-phosphate by C-13-NMR. The identity of the phosphate ester was also confirmed by GC-RLS analysis after further p urification.