Synthesis of fructans by fructosyltransferase from the tuberous roots of Viguiera discolor (Asteraceae)

Sucrose:sucrose fructosyltransferase (SST) and fructan:fructan fructosyl-tr ansferase (FFT) activities from crude extracts of tuberous roots of Viguier a discolor growing in a preserved area of cerrado were analyzed in 1995-199 6. SST activity was characterized by the synthesis of 1-kestose from sucros e and FFT activity by the production of nystose from 1-kestose. The highest fructan-synthesizing activity was observed during early dormancy (autumn), when both (SST and FFT) activities were high. The increase in synthetic ac tivity seemed to start during the fruiting phase in the summer, when SST ac tivity was higher than in spring. During winter and at the beginning of spr outing, both activities declined. The in vitro synthesis of high molecular mass fructans from sucrose by enzymatic preparations from tuberous roots co llected in summer showed that long incubations of up to 288 h produced cons istently longer polymers which resembled those found in vivo with respect t o chromatographic profiles.