A cyclic β-1,2-glucan synthetase was solubilized by sonicating 100,000 × g pellets of the crude extract of Agrobacterium radiobacter IFO 12665 A1-5 in the presence of ethylenediaminetetraacetic acid. The enzyme was separated by DEAE-Sephadex column chromatography into adsorbed and nonadsorbed fractions (cyclic β-1,2-glucan synthetases I and II, respectively). Both enzymes were further purified by Toyo-pearl HW55 gel filtration and high performance liquid chromatography on Shodex WS-803. Neither enzyme could penetrate into 4% polyacrylamide gel in sodium dodecyl sulfate polyacrylamide gel electrophoresis. The specific activity of synthetase I was 9.5 × 10−4 units/mg and it was purified 26-fold from the crude extract with a yield of 1.9%. Synthetase I was optimal at 33°C and pH 8-9 for the enzyme reaction. The activity was almost stable up to 40°C for 30 min, and mostly inactivated at 50°C for 30 min. The enzyme activity was stimulated about three times with the addition of 10-20 mM FeCl3. The enzyme produced the same cyclic β-1,2-glucan with a polymerization degree of 17-24 from UDP-glucose that the cell produced. The specific activity of synthetase II was 23.6 × 10−4 units/mg and it was purified 60-fold from the crude extract with a yield of 2.3%.

• Compound ID: 1077
  

  Cyclic -2)-b-D-Glcp-(1-

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  Structure type: cyclic polymer repeating unit ; n=17-24
  Trivial name: cyclosophoran, cyclic β-1,2-glucan, periplasmic cyclic β-1,2-glucan, cyclosophorans
  Compound class: EPS
  Reference(s) to other database(s): GTC:G21553SY, GlycomeDB:25048
  
   
  
  Agrobacterium radiobacter IFO 12665 A1-5
  CSDB ID 139750 (all data & tools)