THE MECHANISIM OF FRUCTOSAN METABOLISM IN HIGHER PLANTS AS EXEMPLIFIED IN HELIANTHUS TUBEROSUS

Summary The physiological behaviour of the fructose polymers, which are the sole carbohydrate reserve in Jerusalem artichoke tubers, is briefly described. It is suggested that certain enzymes which have been isolated from this tissue can account for these changes, and a theory of their integrated action is put forward: this involves the trisaccharide IF-fructosylsucrose, widely found in fructosan-containing tissues, as a key intermediate, and the enzyme which produces it from sucrose as a controlling biochemical factor. Sucrose itself, both as a substrate and by its direct effect on the other enzymes, also acts as a major means of control. The hypothesis does not involve sugar phosphates or nucleotide sugars, and seems to be applicable to other plants which contain fructosans.