Table 2.

 . Enzymatic properties of CFT150 and CFT107

Characteristic CFT150 CFT107
Ratio of reaction products (CF6:CF7) 4:1 4:1
Km (mM)a1.564.76
Specific activity (U/mg) 3.58 2.16
kcat (S−1) 15.3 12.2
kcat/Km(mM−1 s−1) 9.80 2.56
Optimal temp (°C) 45 45
Optimal pH 7.5 7.5
ThermostablebLessMore
Inhibition by Cu2+ and Ag+Yes Yes
Intermolecular transfructosylationcYes Yes
Hydrolysis of cycloinulooligosaccharidesdYes Yes
  • a Inulin from dahlia (Sigma) was used. The molecular weight of inulin was assumed to be 5,400.

  • b CFT107 was about 10 to 30% more stable than CFT150 at a range of 30 to 45°C. Both enzymes were not stable at temperatures of >50°C.

  • c Disproportionation and coupling reactions were tested as described previously (9).

  • d The reaction mixture consisted of 50 μl of 0.3% CF6 containing small amounts of CF7 and 50 μl (50 mU, pH 8.0) of the purified His-tagged CFTase. The reaction was carried out at 37 or 45°C for 6 h. The reaction products were analyzed by high-performance liquid chromatography.