Enzymological aspects of de novo synthesis of fructooligosaccharides in leaf disks of certain Asteraceae. IV. The activity of sucrose–sucrose 1-fructosyltransferase
Sucrose–sucrose fructosyltransferase capable of synthesizing the trisaccharide 1F-fructosylsucrose from sucrose was partially purified from crude protein extracts of (1) lettuce leaf disks, which were incubated on a sucrose medium for 72 h, and (2) lettuce leaf midvein–petiole tissue, which normally contains fructosans ranging in degree of polymerization from 3 to about 10–11. Maximum transferase activity was associated with the protein exhibiting an apparent molecular weight of about 100 000 as estimated by gel filtration technique. The transferase was not detected in protein extract of unincubated leaf blade tissue. Evidence presented strongly suggests that the transferase was synthesized de novo in response to incubation of leaf disks on sucrose medium.