Fructan depolymerization

Three enzymes, sucrose sucrose 1-fructosyl transferase (1-SST), fructan fructan 1-fructosyl transferase (1-FFT), and 1-fructan-p-fructosidase (1-FEH), appear to control fructan polymerization and depolymerization in the Jerusalem artichoke. Each is sequestered in the vacuole of the cells in which they are expressed and has a pH optimum in the acid range (pH 5.0 to 5.5), in keeping with a vacuolar origin (Frehner et al., 1984). 

FIGURE 10.20 The action of fructan 1-exohydrolase and fructan fructan 1-fructosyltransferase in dormant and sprouting tubers on inulin depolymerization. Abbreviations 1-feh = fructan 1-exohydrolase 1-fft = fructan fructan 1-fructosyltransferase hk = hexokinase spp = sucrose phosphate phosphatase sps = sucrose phosphate synthase GF = sucrose G = glucose F = fructose GFF = 1-ketose GF-P = sucrose phosphate UDP-G = uridine diphosphate glucose F-6-P = fructose-6-phosphate. 

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